FLUX Mentor Class-A dual-mono headphone amplifier
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Flux Lab Acoustics
Flux Lab Acoustics is a Ukrainian company dedicated to the design and manufacturing of high-end audio products. The company is well regarded in the audiophile community and their portfolio includes many successful and well awarded products, like the Flux FCN-10 or the FA-12 headphone amplifiers. Their products are famous for combining excellent sonic performance and build quality at very reasonable prices.
The Russian invasion of Ukraine ruined their business and Flux Lab Acoustics was forced to cease production. Thankfully none of the team or their families was fatally wounded and now that the Russians have retreated back, Flux were able to resume production at their own facilities in Kharkiv.
Their new creation is the Mentor, a headphone amplifier born during war, under very difficult conditions and this means a lot about the dedication and the internal strength of the Flux Lab team.
Flux Mentor
The Flux Mentor is a Class-A, dual mono headphone amplifier with many technical innovations
The output stage operates in class A, which allows transmitting signals of small amplitude with the highest accuracy. The amplifier circuitry uses J-Fet transistors at the input for a meaty and smooth sound, and bipolar transistors at the output, specially designed for use in high-end audio circuits, to deliver the highest fidelity and transparency. The power supply for the amplifier circuitry is 70 volts to ensure uncompromising dynamic performance with the most demanding headphones on the market.
Class-A produces a lot of heat that needs to be effectively dissipated and in order to do so, Flux have refined the heat sink design. The amplifier circuitry is promptly prepared for utilization, and subsequently shares its greatest sound quality only after a mere 15 minutes. In addition they have partially placed the heat sink under some of the PCB components, which allows the amplifier circuitry to start up faster and provides better thermal stability for the entire circuitry.
The amplifier is built on the dual mono principle, with each channel having its own power supply and power transformer. The power supply for each channel uses four high-capacity capacitors manufactured by Cornell Dubilier Electronics, capable of delivering significant current at their output and having a low output impedance.
The power supply utilizes custom power transformers with a very low dissipation field and noise. This permits the amplifier circuit to function without any apparent hum, even when using high-sensitivity headphones. Flux have also used an Ultra Pure Oxygen Free Copper (UP-OFC) power cable with additional shielding from Neotech from the AC inlet socket to the power transformers.
The volume control is based on a relay attenuator and contains 64 steps. The control circuit uses Panasonic fast signal relays with low contact resistance. The analog signal is fed to the relay attenuator located next to the input sockets, and the ALPS variable potentiometer (Blue Velvet series) is used for control only.
The Flux Mentor supports a feature that allows the synchronization of two amplifier units in a dual mono mode for an even greater power reserve. Each channel of the amplifier operates in a fully balanced mode. You simply select which unit is the master and which is the slave. The synchronization system also allows you to control the operation of the second amplifier, so that when the master unit is switched on, the second unit is automatically switched on.
A dual mono Mentor stuck in mono mode is able to produce 33.5W RMS per channel at 32Ω and 6.4W RMS per channel at 300Ω, a huge amount of power that can ransack every headphone in existence or even run your speakers. You can order the Mentor with or without the mono module.
FLUX guarantees an absolutely identical volume level between the two units, even if the second unit is purchased much later. The differences may be primarily due to the tone of the front panels, as there are slight differences from batch to batch.
Components and PCB
The high quality components used in the circuits include Takman resistors (Rex and Rey series), extremely expensive Vishay VAR series uncased audio resistors, PRP resistors, Cornell Dubilier, Nichicon, Wima, and Epcos capacitors.
The internal PCB features exquisite craftsmanship, most components are through hole, the quality of the soldering, the cabling and the assembly are really marvelous.
Remote control
The Mentor supports remote control for volume adjustment and mute/unmute functions.
The high quality, all aluminum, remote control is optional and available for $50 extra. It could have been included as a standard but on the other hand it saves some money for people who don't need one.
The remote control adjusts the volume without moving the volume knob. Every time you touch the knob, the volume automatically reverts to its given position.
Power cable upgrade
The designer suggests that you will get the most out of the Mentor only if you use a high quality power cable. You can use your favorite brand or consider Flux Lab custom-made power cable. It is based on an NEP-5002 conductor from Neotech that features thick conductors (0.42mm) of ultra-pure oxygen-free copper (UP-OFC). The ground conductor’s smaller cross-section (1.43mm) results in a slim and flexible cable for a better user experience. The cable provides complete protection from external electromagnetic radiation, thanks to an internal aluminum foil shield and a drain wire. Filling the free volume with synthetic fiber ensures comfortable flexibility and a “memory” effect, allowing the cable to be easily positioned and maintained in the desired position. Each cable is hand-crafted in the Flux Lab workshop and equipped with high-quality TTAF 93047/048 connectors with gold-plated brass and copper contact groups. The cable is supplied in a length of 1.8 meters (6 feet) and is available as a $100 extra purchase when you place your order for the Mentor.
Non Audio stuff
The chassis of the Mentor is made from black painted metal sheet. The front panel and the impressively massive volume knob, which is custom made, are from one piece, solid aluminum alloy. They are painted with a high quality and very smooth finish that is available in two color options, titanium gray and coal black.
The sturdy and well made chassis comes with four anti-vibration feet installed as a standard.
The only thing of note is the rather odd shape of the chassis which measures 342x397x82mm thus making it more deep and less wide than the industry standard so you might have a problem placing it above or underneath other audio components.
The Flux Mentor is a headphone amplifier without a preamplifier output function or any digital inputs. It has balanced XLR and single ended RCA line inputs that are located at the back of the unit. You can have both of them simultaneously plugged in and select the desired one from the corresponding switch at the front. The back also houses the AC input and the optional synchronization interface.
The minimalist front face has power on/off, input and gain switches located at the left, the dominating volume knob at the middle and two headphone outputs at the right. The first is a combined 6.35mm jack and 3-pin XLR for the mono mode while the second is a 4-pin XLR.
Let's talk about power
The power output of a single Mentor is 11.2W (32Ω) and 1.6W (300Ω) RMS per channel so it easily ranks amongst the most powerful amplifiers in the market. In order to cater for different headphone loads, Flux have included three gain settings (low-14dB, medium-20dB and high-25.3dB) that can be selected from a switch at the front panel.
The stepped attenuator is well programmed and makes fine adjustments with every “click”, not too loud, not too quiet. To get a rough idea about the power output and the volume adjustment range of the Mentor, the Focal Clear Mg needs about 21 steps to get from silence to pretty loud at low gain setting and the HIFIMAN Susvara 30 steps at high gain. Volume alone doesn't mean much though, what matters the most is that the Mentor drives the Susvara with great dynamic range, excellent control, strong grip and surplus of headroom.
The Mentor is a powerhouse but the low gain is so well designed that it can also drive sensitive earphones without getting loud too early. As an example, the FiiO FX15 needs 18 steps to get comfortably loud.
The Flux Mentor doesn't get hot as other Class-A amplifiers, it only becomes mildly warm under the bottom of the chassis. The rest of the chassis stays cool even under stress conditions.
As per usual practice the Flux Mentor was left playing music for about 150 hours before listening evaluation.
The Flux Mentor was tested with the Neotech power upgrade cable.
All headphone cables that were used during the evaluation are made by Lavricables.
Audio stuff
The Mentor is dead silent without the faintest background hiss even when used with very sensitive earphones. A pitch black background that helps all the finest sonic particles to emerge and surface from the depths of the recording in a pure and naturally flowing way so the sound is full of detail but never becomes analytical or sterile. The sound of silence is audible and extremely beneficial for the sonic performance of the Mentor which has an eerie and spooky calmness, a quietness that only the best “high end” amplifiers have.
You don't have to listen a lot in order to realize that the Flux Mentor has class leading transparency and impressive scaling potential. It is a high-end amplifier with a mirror-like fidelity that must be paired with the best possible sources in order to unveil its full glory. The Mentor will never become the bottleneck of your system, no matter how good your source and your headphones are, it will always deliver its best and make sure to highlight every last bit of their unique sonic characteristics. On the contrary, there is a strong possibility that source and headphones might become the limiting factors if they are not up to the task.
I have started my listening sessions with trusted mid-range sources, like the Aune X8 XVIII and the Volumio Primo, soon to discover that despite having good results from the beginning, I always felt that the Mentor could do much better.
My next move was to switch to the HIFIMAN Serenade, the Denafrips Pontus II and the Lab 12 dac1 reference (custom edition) that all of them perform admirably well, greatly surpassing their asking price. At last, now everything felt at place and the combination unveiled all the sonic virtues of the Flux Mentor or the Mentor unveiled all the sonic virtues of the sources, read it the way you like! Still I am pretty sure that if I owned better sources, the Mentor could have sounded even better.
The Mentor is not some kind of a snobbish amplifier though, you can always enjoy it with your favorite sources in a never ending musical journey that might eventually lead you to an upgrade path.
With the Mentor there is no such thing as headphone matching, the amplifier pairs exemplary well with virtually all kinds of headphones as it mirrors their own sound signature with the most impressive fidelity. I have enjoyed pretty much everything, from the Sennheiser HD660S2 to the HIFIMAN Arya Organic, the Meze Elite and the HIFIMAN Susvara. The better the headphone I used, the better was the performance of the Mentor.
At this point someone could rightfully ask - is the Flux Mentor like a “wire with gain” kind of an amplifier? The only things you have been talking about are fidelity and transparency.
Well, not exactly, the Mentor is exactly the opposite, this is an amplifier painstakingly tuned by ear to combine transparency and fidelity with deep musicality and astonishing levels of engagement. It took months of fine tuning to give Mentor its sound signature which is flowing, effortless, natural, immersive and communicative without calling attention to itself.
The amplifier is synonymous with precision and calmness, it is not producing short lived glowing pyrotechnics that may sound impressive and imposing at the beginning but fail to communicate the true essence of the music at the end.
The Mentor is a silent force, a mature and sophisticated sounding amplifier that very carefully balances technicalities and musicality in the exact needed amounts to make your music sound as realistic as possible while at the same time respecting the sonic characteristics of the source and the headphones used.
The amplifier is dynamic and impactful but not in a brutal way, it is fast, precise and accurate with crystalline clarity and strong presence in the whole frequency range but everything is done in a way that oozes aristocratic politeness. The Mentor is not raw or bold sounding, this is an intellectual amplifier that will play with your mind and heart rather than excite your primitive instincts.
Music break
One of the albums that I have listened with the Mentor was Handel's opera Alcina. The listening experience with the Mentor and the Lab 12 dac1 reference was simply magnificent. I have used both the Susvara and the Elite.
More audio stuff
The overall resolution and refinement of the Mentor are astounding, especially in the treble which sounds silky smooth and ethereal but never lacking in extension and energy. The mid-range is larger than life, spacious, and articulated with natural voicing while the bass has impressive layering and definition. The timbre is extra natural and realistic with the most organic characteristics. Acoustic music sounds convincingly lifelike while the Mentor has all the technical prowess to handle all kinds of music.
The sound is smooth and mildly warm but not mellow or dark, the flowing music is full of colorful harmonies and overtones, like a meadow full of spring flowers and thousands of butterflies. The texture is weighty and and visceral, every single note is heard weighty and full of substance. The amplifier has excellent timing, the music fades away in the most natural manner, not fast not too slow, the time that passes for the moment a note is born till it dies is exactly as it was captured in the recording.
The soundstage of the Mentor is both deep and expanded but in a natural way without artificiality added width or depth. Separation is phenomenal, both in the vertical and horizontal plane, the Mentor has class leading positioning accuracy and imaging. The presentation is grand and holographic, the listening experience is immersive, large symphonic works sound really impressive, the listener feels like sitting a couple of rows behind the conductor, enjoying the full glory of the symphony orchestra which is re-created with a finely sculptured relief. The Mentor also excels in reproducing all the ambient information that was captured in a high quality recording thus making the listening experience even more realistic.
The competition
Other solid state amplifiers that I have reviewed and are worth mentioning as possible alternatives to the Flux Mentor are the Violectric V222, V340 and V550. The sonic characteristics of the Mentor are rather closer to the flagship V550 than the other two models. The V222 is warmer with a more tube-like character but it can't match the precision, the resolution and the transparency of the Mentor while the V340 gets close enough but not as much as the V550.
The truth is that the Violectric V550 and the Flux Mentor share a lot of common characteristics regarding their transparency, precision and mirror-like fidelity. Additionally both sound musical and engaging and none of them is clinical or sterile despite their flagship technicalities.
A difference is that the Flux Mentor is a calmer and more polite amplifier, the sound approach is more sophisticated and civilized when compared with the muscular brutality and the raw power of the Violectric V550. The V550 is more impactful on the low-end and energetic in the treble while it has an edge when it comes to overall clarity and transparency. What doesn't have though is that delightful Class-A timbre of the Mentor which makes it sound more organic and natural than the V550, the music has better fluidity and a greater sense of realism in the Flux Mentor that is additionally more holographic and immersive sounding than its German colleague.
The Violectric V550 is also a high-end balanced preamplifier and is built around an all aluminum chassis but it is considerably more expensive than the Flux Mentor and you have to spend even more money to upgrade to the V550 PRO in order to get a stepped attenuator that is included as a standard in the Flux Mentor.
Conclusion
Some of the best human creations were made during war time. The Flux Mentor is a masterpiece, a mature and very sophisticated amplifier that has all the right ingredients in the exact needed amounts to make the perfect sonic dish. Honestly, high-end was never so affordable before the making of the Flux Mentor. The Flux Lab Acoustics have made an end-game solid state amplifier that you can buy and stop worrying about future upgrades. The Flux Mentor is easily the most affordable, high-end headphone amplifier on the planet with an insane value for money ratio and one of the best - if not the best - bargains in the audio industry.
The review sample was kindly provided free of charge in exchange for an honest review.
The Flux Mentor is available from here. The base price for a single Flux Mentor is $1229 and $1299 with the additional mono input so a dual mono set-up costs $2599. All orders are dispatched from a warehouse in Poland so EU customers will not have to deal with import fees and tax.
A deluxe version of the review is available in my website.
This is the world premiere review of the FLUX Mentor headphone amplifier.
Flux Lab Acoustics is a Ukrainian company dedicated to the design and manufacturing of high-end audio products. The company is well regarded in the audiophile community and their portfolio includes many successful and well awarded products, like the Flux FCN-10 or the FA-12 headphone amplifiers. Their products are famous for combining excellent sonic performance and build quality at very reasonable prices.
The Russian invasion of Ukraine ruined their business and Flux Lab Acoustics was forced to cease production. Thankfully none of the team or their families was fatally wounded and now that the Russians have retreated back, Flux were able to resume production at their own facilities in Kharkiv.
Their new creation is the Mentor, a headphone amplifier born during war, under very difficult conditions and this means a lot about the dedication and the internal strength of the Flux Lab team.
Flux Mentor
The Flux Mentor is a Class-A, dual mono headphone amplifier with many technical innovations
The output stage operates in class A, which allows transmitting signals of small amplitude with the highest accuracy. The amplifier circuitry uses J-Fet transistors at the input for a meaty and smooth sound, and bipolar transistors at the output, specially designed for use in high-end audio circuits, to deliver the highest fidelity and transparency. The power supply for the amplifier circuitry is 70 volts to ensure uncompromising dynamic performance with the most demanding headphones on the market.
Class-A produces a lot of heat that needs to be effectively dissipated and in order to do so, Flux have refined the heat sink design. The amplifier circuitry is promptly prepared for utilization, and subsequently shares its greatest sound quality only after a mere 15 minutes. In addition they have partially placed the heat sink under some of the PCB components, which allows the amplifier circuitry to start up faster and provides better thermal stability for the entire circuitry.
The amplifier is built on the dual mono principle, with each channel having its own power supply and power transformer. The power supply for each channel uses four high-capacity capacitors manufactured by Cornell Dubilier Electronics, capable of delivering significant current at their output and having a low output impedance.
The power supply utilizes custom power transformers with a very low dissipation field and noise. This permits the amplifier circuit to function without any apparent hum, even when using high-sensitivity headphones. Flux have also used an Ultra Pure Oxygen Free Copper (UP-OFC) power cable with additional shielding from Neotech from the AC inlet socket to the power transformers.
The volume control is based on a relay attenuator and contains 64 steps. The control circuit uses Panasonic fast signal relays with low contact resistance. The analog signal is fed to the relay attenuator located next to the input sockets, and the ALPS variable potentiometer (Blue Velvet series) is used for control only.
The Flux Mentor supports a feature that allows the synchronization of two amplifier units in a dual mono mode for an even greater power reserve. Each channel of the amplifier operates in a fully balanced mode. You simply select which unit is the master and which is the slave. The synchronization system also allows you to control the operation of the second amplifier, so that when the master unit is switched on, the second unit is automatically switched on.
A dual mono Mentor stuck in mono mode is able to produce 33.5W RMS per channel at 32Ω and 6.4W RMS per channel at 300Ω, a huge amount of power that can ransack every headphone in existence or even run your speakers. You can order the Mentor with or without the mono module.
FLUX guarantees an absolutely identical volume level between the two units, even if the second unit is purchased much later. The differences may be primarily due to the tone of the front panels, as there are slight differences from batch to batch.
Components and PCB
The high quality components used in the circuits include Takman resistors (Rex and Rey series), extremely expensive Vishay VAR series uncased audio resistors, PRP resistors, Cornell Dubilier, Nichicon, Wima, and Epcos capacitors.
The internal PCB features exquisite craftsmanship, most components are through hole, the quality of the soldering, the cabling and the assembly are really marvelous.
Remote control
The Mentor supports remote control for volume adjustment and mute/unmute functions.
The high quality, all aluminum, remote control is optional and available for $50 extra. It could have been included as a standard but on the other hand it saves some money for people who don't need one.
The remote control adjusts the volume without moving the volume knob. Every time you touch the knob, the volume automatically reverts to its given position.
Power cable upgrade
The designer suggests that you will get the most out of the Mentor only if you use a high quality power cable. You can use your favorite brand or consider Flux Lab custom-made power cable. It is based on an NEP-5002 conductor from Neotech that features thick conductors (0.42mm) of ultra-pure oxygen-free copper (UP-OFC). The ground conductor’s smaller cross-section (1.43mm) results in a slim and flexible cable for a better user experience. The cable provides complete protection from external electromagnetic radiation, thanks to an internal aluminum foil shield and a drain wire. Filling the free volume with synthetic fiber ensures comfortable flexibility and a “memory” effect, allowing the cable to be easily positioned and maintained in the desired position. Each cable is hand-crafted in the Flux Lab workshop and equipped with high-quality TTAF 93047/048 connectors with gold-plated brass and copper contact groups. The cable is supplied in a length of 1.8 meters (6 feet) and is available as a $100 extra purchase when you place your order for the Mentor.
Non Audio stuff
The chassis of the Mentor is made from black painted metal sheet. The front panel and the impressively massive volume knob, which is custom made, are from one piece, solid aluminum alloy. They are painted with a high quality and very smooth finish that is available in two color options, titanium gray and coal black.
The sturdy and well made chassis comes with four anti-vibration feet installed as a standard.
The only thing of note is the rather odd shape of the chassis which measures 342x397x82mm thus making it more deep and less wide than the industry standard so you might have a problem placing it above or underneath other audio components.
The Flux Mentor is a headphone amplifier without a preamplifier output function or any digital inputs. It has balanced XLR and single ended RCA line inputs that are located at the back of the unit. You can have both of them simultaneously plugged in and select the desired one from the corresponding switch at the front. The back also houses the AC input and the optional synchronization interface.
The minimalist front face has power on/off, input and gain switches located at the left, the dominating volume knob at the middle and two headphone outputs at the right. The first is a combined 6.35mm jack and 3-pin XLR for the mono mode while the second is a 4-pin XLR.
Let's talk about power
The power output of a single Mentor is 11.2W (32Ω) and 1.6W (300Ω) RMS per channel so it easily ranks amongst the most powerful amplifiers in the market. In order to cater for different headphone loads, Flux have included three gain settings (low-14dB, medium-20dB and high-25.3dB) that can be selected from a switch at the front panel.
The stepped attenuator is well programmed and makes fine adjustments with every “click”, not too loud, not too quiet. To get a rough idea about the power output and the volume adjustment range of the Mentor, the Focal Clear Mg needs about 21 steps to get from silence to pretty loud at low gain setting and the HIFIMAN Susvara 30 steps at high gain. Volume alone doesn't mean much though, what matters the most is that the Mentor drives the Susvara with great dynamic range, excellent control, strong grip and surplus of headroom.
The Mentor is a powerhouse but the low gain is so well designed that it can also drive sensitive earphones without getting loud too early. As an example, the FiiO FX15 needs 18 steps to get comfortably loud.
The Flux Mentor doesn't get hot as other Class-A amplifiers, it only becomes mildly warm under the bottom of the chassis. The rest of the chassis stays cool even under stress conditions.
As per usual practice the Flux Mentor was left playing music for about 150 hours before listening evaluation.
The Flux Mentor was tested with the Neotech power upgrade cable.
All headphone cables that were used during the evaluation are made by Lavricables.
Audio stuff
The Mentor is dead silent without the faintest background hiss even when used with very sensitive earphones. A pitch black background that helps all the finest sonic particles to emerge and surface from the depths of the recording in a pure and naturally flowing way so the sound is full of detail but never becomes analytical or sterile. The sound of silence is audible and extremely beneficial for the sonic performance of the Mentor which has an eerie and spooky calmness, a quietness that only the best “high end” amplifiers have.
You don't have to listen a lot in order to realize that the Flux Mentor has class leading transparency and impressive scaling potential. It is a high-end amplifier with a mirror-like fidelity that must be paired with the best possible sources in order to unveil its full glory. The Mentor will never become the bottleneck of your system, no matter how good your source and your headphones are, it will always deliver its best and make sure to highlight every last bit of their unique sonic characteristics. On the contrary, there is a strong possibility that source and headphones might become the limiting factors if they are not up to the task.
I have started my listening sessions with trusted mid-range sources, like the Aune X8 XVIII and the Volumio Primo, soon to discover that despite having good results from the beginning, I always felt that the Mentor could do much better.
My next move was to switch to the HIFIMAN Serenade, the Denafrips Pontus II and the Lab 12 dac1 reference (custom edition) that all of them perform admirably well, greatly surpassing their asking price. At last, now everything felt at place and the combination unveiled all the sonic virtues of the Flux Mentor or the Mentor unveiled all the sonic virtues of the sources, read it the way you like! Still I am pretty sure that if I owned better sources, the Mentor could have sounded even better.
The Mentor is not some kind of a snobbish amplifier though, you can always enjoy it with your favorite sources in a never ending musical journey that might eventually lead you to an upgrade path.
With the Mentor there is no such thing as headphone matching, the amplifier pairs exemplary well with virtually all kinds of headphones as it mirrors their own sound signature with the most impressive fidelity. I have enjoyed pretty much everything, from the Sennheiser HD660S2 to the HIFIMAN Arya Organic, the Meze Elite and the HIFIMAN Susvara. The better the headphone I used, the better was the performance of the Mentor.
At this point someone could rightfully ask - is the Flux Mentor like a “wire with gain” kind of an amplifier? The only things you have been talking about are fidelity and transparency.
Well, not exactly, the Mentor is exactly the opposite, this is an amplifier painstakingly tuned by ear to combine transparency and fidelity with deep musicality and astonishing levels of engagement. It took months of fine tuning to give Mentor its sound signature which is flowing, effortless, natural, immersive and communicative without calling attention to itself.
The amplifier is synonymous with precision and calmness, it is not producing short lived glowing pyrotechnics that may sound impressive and imposing at the beginning but fail to communicate the true essence of the music at the end.
The Mentor is a silent force, a mature and sophisticated sounding amplifier that very carefully balances technicalities and musicality in the exact needed amounts to make your music sound as realistic as possible while at the same time respecting the sonic characteristics of the source and the headphones used.
The amplifier is dynamic and impactful but not in a brutal way, it is fast, precise and accurate with crystalline clarity and strong presence in the whole frequency range but everything is done in a way that oozes aristocratic politeness. The Mentor is not raw or bold sounding, this is an intellectual amplifier that will play with your mind and heart rather than excite your primitive instincts.
Music break
One of the albums that I have listened with the Mentor was Handel's opera Alcina. The listening experience with the Mentor and the Lab 12 dac1 reference was simply magnificent. I have used both the Susvara and the Elite.
More audio stuff
The overall resolution and refinement of the Mentor are astounding, especially in the treble which sounds silky smooth and ethereal but never lacking in extension and energy. The mid-range is larger than life, spacious, and articulated with natural voicing while the bass has impressive layering and definition. The timbre is extra natural and realistic with the most organic characteristics. Acoustic music sounds convincingly lifelike while the Mentor has all the technical prowess to handle all kinds of music.
The sound is smooth and mildly warm but not mellow or dark, the flowing music is full of colorful harmonies and overtones, like a meadow full of spring flowers and thousands of butterflies. The texture is weighty and and visceral, every single note is heard weighty and full of substance. The amplifier has excellent timing, the music fades away in the most natural manner, not fast not too slow, the time that passes for the moment a note is born till it dies is exactly as it was captured in the recording.
The soundstage of the Mentor is both deep and expanded but in a natural way without artificiality added width or depth. Separation is phenomenal, both in the vertical and horizontal plane, the Mentor has class leading positioning accuracy and imaging. The presentation is grand and holographic, the listening experience is immersive, large symphonic works sound really impressive, the listener feels like sitting a couple of rows behind the conductor, enjoying the full glory of the symphony orchestra which is re-created with a finely sculptured relief. The Mentor also excels in reproducing all the ambient information that was captured in a high quality recording thus making the listening experience even more realistic.
The competition
Other solid state amplifiers that I have reviewed and are worth mentioning as possible alternatives to the Flux Mentor are the Violectric V222, V340 and V550. The sonic characteristics of the Mentor are rather closer to the flagship V550 than the other two models. The V222 is warmer with a more tube-like character but it can't match the precision, the resolution and the transparency of the Mentor while the V340 gets close enough but not as much as the V550.
The truth is that the Violectric V550 and the Flux Mentor share a lot of common characteristics regarding their transparency, precision and mirror-like fidelity. Additionally both sound musical and engaging and none of them is clinical or sterile despite their flagship technicalities.
A difference is that the Flux Mentor is a calmer and more polite amplifier, the sound approach is more sophisticated and civilized when compared with the muscular brutality and the raw power of the Violectric V550. The V550 is more impactful on the low-end and energetic in the treble while it has an edge when it comes to overall clarity and transparency. What doesn't have though is that delightful Class-A timbre of the Mentor which makes it sound more organic and natural than the V550, the music has better fluidity and a greater sense of realism in the Flux Mentor that is additionally more holographic and immersive sounding than its German colleague.
The Violectric V550 is also a high-end balanced preamplifier and is built around an all aluminum chassis but it is considerably more expensive than the Flux Mentor and you have to spend even more money to upgrade to the V550 PRO in order to get a stepped attenuator that is included as a standard in the Flux Mentor.
Conclusion
Some of the best human creations were made during war time. The Flux Mentor is a masterpiece, a mature and very sophisticated amplifier that has all the right ingredients in the exact needed amounts to make the perfect sonic dish. Honestly, high-end was never so affordable before the making of the Flux Mentor. The Flux Lab Acoustics have made an end-game solid state amplifier that you can buy and stop worrying about future upgrades. The Flux Mentor is easily the most affordable, high-end headphone amplifier on the planet with an insane value for money ratio and one of the best - if not the best - bargains in the audio industry.
The review sample was kindly provided free of charge in exchange for an honest review.
The Flux Mentor is available from here. The base price for a single Flux Mentor is $1229 and $1299 with the additional mono input so a dual mono set-up costs $2599. All orders are dispatched from a warehouse in Poland so EU customers will not have to deal with import fees and tax.
A deluxe version of the review is available in my website.
This is the world premiere review of the FLUX Mentor headphone amplifier.
Ichos
Ohh, it's been quite a while since I tested this combo. Difficult to compare now, I think that the Oor is not as refined and silky while I could say that it is drier and more sterile than the Mentor. Take this with a grain of salt though.
Ichos
I believe that they are on the same level but have a different approach. The Oor has the tendency to highlight its technical performance while the Mentor has it on the background to serve the music.
