Matrix M-Stage HPA-3B: The Balanced Revolution

2017-06-28 10:30Reviews

Me: I am an amateur musician & avid admirer of music. I would like to call myself a music enthusiast, rather than an audiophile. I was inspired by music since childhood, and as the time passed, the passion of music grew in me, and that subsequently led me to join Head-Fi. I usually like to listen to Indian Classical Music along with Bollywood songs. My main listening genres include classical, vocal, instrumental, jazz and sometimes pop. With time, my sonic preferences have very much grown. I avidly admire transparency, accuracy along with neutrality, I mostly listen to full sized open back headphones and my favorite headphone is AKG K812, which I run from solid state amplifier. I prefer & admire transparent solid state headphone amplifiers simply because they provide best possible accuracy, transparency & reliability.

I am an average consumer & a humble enthusiast, I like to pen down my thoughts, & I love to express my feelings. I do not receive for any sort financial benefits through this review. My articles are a purely honest writeup aimed for fellow enthusiasts here at Head-Fi community. My profound thanks to Matrix Audio for arranging a sample unit of HPA3-B for my evaluation.

Intro: Matrix Electronic Technology Co. Ltd., located in Xi'an Economic and Technological Development Zone, in the ancient city of Xian. Matrix is an enterprise that dedicates to development & manufacturing of high-fidelity audio products. Matrix has its own highly qualified R&D team, which designs all of their products. I assume we all heard of matrix only since its release of M-Stage headphone amplifier around 2010 which stirred the headphone amp market & was extremely well received across the world; hence It became a benchmark device. I’m a proud owner of Matrix’s HPA-1 & HPA-2, over more than two years. I loved them a lot, had a wonderful time with both of them. The M-Stage amplifier will get updates in circuit board every two years. The latest model is HPA-3, improvised on previous designs.


HPA-1 was warmest & ‘smoothest’ sounding of all three, but had mediocre inbuilt DAC, plus slightly audible noise floor. It had the original BCL style gain switches. HPA-2 largely improvised from HPA-1, applied better performing 24/192 DAC but with fixed +15dB gain. Also, the benchmark bass ‘bump’ has vastly reduced, with much better cleaner & flatter output. Their latest release is HPA-3, is the successor to HPA-2. The HPA-3 has two variants, HPA-3U a Single end headphone amplifier with inbuilt DAC, whereas the HPA-3B, truly balanced headphone amplifier without inbuilt DAC. Both these models are remarkably transparent, without any emphasis or ‘bumps’ which I feel , is a result of improvised design. Now I am writing about HPA-3B, which has an entirely new design with true balanced circuitry. It is priced exactly same as HPA-3U, but this is a pure balanced headphone amplifier (minus inbuilt DAC & RCA outputs)


Technical specifications of HPA-3B:

Balance Headphone Output

SNR: >-114dB A-Weighting

THD+N: <0.0003% at 300ohms 135mW 1kHz A-Weighting

Frequency Response: 20Hz-20kHz (+0dB/-0.05dB)

Output Impedance: 0.6ohms

Output Power: 3800mW at 33ohms / 1500mW at 300ohms / 800mW at 600ohms at THD+N=0.01%

Single End Headphone Output

SNR: >-108dB A-Weighting

THD+N: <0.0004% at 300ohms 325mW 1kHz A-Weighting

Frequency Response: 20Hz-20kHz (+0.03dB/-0.1dB)

Output Impedance: 0.4ohms

Output Power: 2100mW at 33ohms / 430mW at 300ohms / 220mW at 600ohms at THD+N=0.01%

Gain Control: 5dB 10dB 20dB

Power: 230V/115V (Adjustable) 50/60Hz

Power Consumption: <25W

Fuse: AC250V/500mA 5x20mm

Packaging & Accessories: The HPA-3B comes packed in Matrix Audio’s strong cardboard box with foam protection inside & necessary accessories included in the package. Same packaging as of HPA-3U


Included Accessories

User manual & Driver CD: Contains instruction about operating the device & some warranty information. A compact disk is included.

XLR/RCA Adapter : To connect Single end RCA Input to the amp.

Power Cable: AC power cord to attach to mains supply.

Design and Build: The HPA-3U a marvellous & Robust build quality, obviously similar to HPA-3U. Just connections have been changed. On the front side, we have Volume control knob, headphone jack is present in 6.5mm & 4 pin XLR Balanced jack. On the rear side, we have Power socket & switch, 3 pin XLR input port, along with again switch. Volume control is very sophisticated with Dual RK-27 pots on a single shaft. Headphone socket is neutrik clip type, as from ball bearing type of HPA-3U.


HPA-3B is too capable of handling both 110/220V, whose selection switch is on side of the amp. Plus the AC fuse is accessible right besides it. To remove the case & access the circuitry, one has to remove top four screws using allen keys Size (2 & 2.5) plus additional two side screws on each side, to remove the top cover. One small issue user might face here is: Vents on top cover can attract dust or incase a few water droplets fall down, it will straight on the circuit board & damage the board.


Regarding the Internal components, HPA-3B has an entirely new fully balanced circuit board with has double sided PCB with no manual wirings except the toroidal transformer joints. Components are placed in a symmetrical & neat fashion. All components used are carefully selected similar to that of its 3U counterpart, Special dual Alps-27 blue velvet pot on a single shaft (pure balanced pot), the only replaceable part here are the op-amp sockets. HPA-3B contains two sockets of dual op-amp each. Board is excellently soldered and has a reliable workmanship. The HPA-3B runs warm by temperature due to being Class-A, just similar to HPA-3U.


Points : 9.5 out of 10, excellent build in every inch, very similar to HPA-3U

Sound: The HPA-3B puts out a very impressive sound quality, transparency & soundstage due to its balanced design. New performance altogether. The M-Stage has always been a strong & reliable amp, It does not any particular coloration of its own. Soundstage in HPA-3B is amazing . It has a fully circular 3D imaging. Detail retrieval, and dynamics are excellent. Overall the sonic presentation contains high level of transparency and accuracy. Absolutely zero audible hiss/noise, and zero EMI pickup. Dual Alps blue velvet pot does an amazing job of controlling volume very precisely without any channel imbalance & noise with retaining maximum sound quality. Another plus point here is, the HPA-3B has relay mechanism which prevent any noise pop’s when headphones are plugged in/out. This way, a better safety is guaranteed for the precious headphones.


Op-Amp: Stock op-amp ‘s are LME49860 (X2 quantity) from Texas Instruments, which does a good job by default. To test if the HPA-3 scales with better op-amps, I tested it with many op-amps, and settled on 4X LME49710HA set on 2 browndogs for 2 sockets. The HPA-3B scales well and supports the replacement op-amp. With LME49710HA, I can hear appreciable improvement from stock ones, with increased soundstage depth, excellent detailing & instrument separation & even more extension in treble. Overall increase in clarity & transparency.


Driving Power: The HPA-3B is highly powerful when it comes to driving headphones @3.8W power in tap. It can damn well drive any headphone in its default gain. Its output impedance is 0.6 ohms, ensures vastly uncoloured & accurate sound quality. Infact, I couldn’t even switch over to 10dB gain switch, because the HPA-3B is so powerful, 5dB gain is more than enough to drive any headphones. HD800 & AKG K702 particularly sound fantastic HPA-3B. It can also drive anything from IEM’s to planar magnetic headphones with ease. Even using the single end output, sound quality is far better than any other single end headphones I have heard till date.

HPA-3B left me highly impressed with its near summit performance. Points: a full 10 out of 10, very impressive.

Comparison: The most capable competitor for HPA-3B under 500$ price is Gustard H10, another excellent standalone headphone amplifier. Let us see how HPA-3B competes against H10.

Sound quality wise, under single end usage, H10 seems to have upper hand than HPA3B. H10 has a more sophisticated gain control, with more gain switches compared to HPA-3B. But when under balanced usage (which H10 does not support) HPA-3B has an clear win. No comparison here, HPA-3B provides ultimate purity. Function wise, HPA-3B is ahead due to its worldwide voltage compatibility & ofcourse the balanced advantage. HPA-3B outperforms H10, owing to fully balanced design.

Another comparison is to HPA-3U, which is HPA-3B’s amp/dac sibling. You may read the review I wrote on HPA-3U a while ago Sound quality & amplification wise no doubt balanced design provides a substantial amount of audible improvement. HPA-3B just does not have a inbuilt DAC. HPA-3U provides more features as it contains an inbuilt 24/192 DAC, RCA outputs, input selection, and thus behaves as all-in-one unit, saving costs of cables, DAC’s etc. HPA-3U is better choice for all in one device by slightly compromising the sound quality.

In the end, if usage is single end only, then Gustard H10 is better suited, Otherwise, If full balanced connection is available, HPA-3B provides ultimate sound quality. If all-in-one unit is desired, then HPA-3U is the way to go. HPA-3B, is the most performing headphone amplifier under 500$ plus, with a fully balanced headphone support. Offers excellent synergy for high end headphones like HD800. Interms of sound quality, HPA-3B outperforms any solid state amplifier, to be tried near its price point. HPA-3B is the best balanced headphone amplifier under 500$ prince point. Offers highest possible value of money.

Conclusion: The HPA-3B continues the legacy & Reputation of M-Stage series forward, with all-new level of performance. Highly recommended for headphone amplifier under half a thousand dollars. Overall its a gem of an amp, but performs extremely well. Highly impressed. The Matrix M-Stage HPA-3B has a benchmark performance. It impressed me not just in sound presentation, but I literally loved every inch of it. The HPA-3B excels in each and every criterion you put through it. Its workmanship is of high standards, and thus very reliable & robust in operation.

Overall, I can award a full 10/10 for HPA-3B owing to its supreme performance in all aspects.