The Questyle CMA 800R Headphone Amplifier

The Questyle CMA 800R looks like a pretty standard headphone amplifier from the outside, but sound created from the collection of components that makes up its guts is far from ordinary.

I have to admit, the curb appeal from outside casing is pretty low for the asking price of $1,500 but for what the CMA “Current Mode” 800R lacks in cosmetic draw, it more than makes up for in actual acoustic sex appeal. The China-based company Questyle kept the external design fairly simple and familiar to the common audiophile box that many current products appeal to. Not that it feels cheap or flimsy, but perhaps just a bit undersold for how well it actually performs. The case color, LEDs and switches feel a bit off the rack, but the dual single ended outputs are a godsend to a reviewer. The most unusual feature of the 800R is really the amplifier’s approach to balanced output. Upon closer inspection of the balanced headphone jack, viewers find only a mysterious 3-pin configuration instead of the stereo 4-pin one might expect. After a quick review of the amplifiers inputs, it becomes obvious that the CMA 800R is intended for balanced use in a monoblock configuration only, one amplifier per side. The corresponding Mono/Stereo switch makes this all too clear. It’s a bold play from Questyle, double down if you want true balanced amplification. This also means your volume control is going to require a little extra knob work to get things rolling correctly, just like Woo’s flagship WA234 monoblocks. All this quirkiness aside, the 800R has it where it counts in the area that brought us all to this party in the first place. Its sonic reproduction was a surprising delight to me, even when flying solo in single ended mode.

 

I was sent one amplifier sample so all critical listening was done via the single ended mode with a wide variety of headphones including the Audeze LCD-3, XC, Oppo’s PM-1, and the Sennheiser HD650.

The power was a-plenty into all the test cans on hand. Decent listening levels with the LCD-3 rang in around 11 o’clock and the volume knob offered a refined resistance to it that was quite pleasant. The overall desktop real estate covered by the 800R is somewhat smaller top-to-bottom than your average solid state amp, but still resides in nearly the same footprint as modern full size desktop pieces like the Auralic VEGA DAC.

The three words that best describe the 800R are: dynamic, accurate and (most importantly) energetic. The first two run-of-the-mill audiophile descriptors should be found in the listening notes of any headphone amplifier north of a grand, but aren’t always. The 800R’s realism star-crossed with speed and comfort make this amplifier stand out in the crowd. Frequency response is flat to the naked ear and bass impact and slam are exactly what you would want from a solid state amplifier. The evenhanded delivery makes it perfectly suited for every genre with no bias in any direction. It’s as clean as a whistle and tight as a tiger. Low end response and extension are as beautiful as almost any amp I’ve laid my ears on, without resorting to extraneous tonal texture or sonic lushness. This is the magical meeting place that culminates around the third descriptor above. The trump card that the 800R brings to the table is it ability to convey spectacular, realistic energy without having to resort to lowbrow tricks or gimmicks. It excels at delivering good clean fun.

When comparing it to other amplifiers, the only product that comes to mind with a similar impact to my memory is the impressive but pricey Luxman P700u, which really set itself apart (but at nearly 4X the cost of the 800R). The same idea applies here. Within the Questyle’s delivery lies an incredibly detailed rendering that manages to resurrect a believable, finely tuned liveliness. What’s in the secret sauce? There seems to be less to point a direct singular finger at in the head amp world than the current DAC or dedicate source market, which is riddled with spec heavy feature sets. The scarce marketing materials for the product would perhaps have us believe its somehow tied into the unique “Current Mode” technology that makes up the 800s namesake. From the Questyle English-translated website:

“CMA800R extends Questyle Audio’s outstanding Current Mode Amplification TM technology, it provides 0.00038% ultra-low distortion, 650KHz wide frequency, 114dB Signal to Noise Ratio…. The Current Mode headphone amplifier is an amplifier that processes signals in current mode, totally different from the traditional way. The Current Mode Amplification consists of the Input Buffer, Current Transmitter, Trans-impedance Amplifier and Output Buffer, each section makes up a TransLiner(TL) loop circuit. CMA technology is traditionally applied in high speed communication and video processing fields, Questyle creatively applied it into audio system and awarded patents. In traditional Voltage Mode amplifier, the Common-emitter voltage amplifier is indispensable but its transistor impedance overloading is too much, so it causes the Miller Effect and greatly slacked its high frequency response. Besides, when the voltage mode amplifier is processing fast speed rising pulse wave and large amplitude HF output, limited by power and capacitor loading, it can definitely cause Transient Intermodulation Distortion (TIMD). TIMD brings a metal sound mixed into music and causes obvious distortion, which gives audience very unpleasant feeling. This is so-called transistor sound. But Current Mode amplifier, the capacitors is between each two transistors which affect speed and band width working in a low impedance resistance, RC value is ultra-low, so it can easily achieve amplification with much broad band and ultra-low distortion, avoid TIMD.”

I actually knew a Tim D back in high school that played in a band and he definitely brought the metal sound with him so perhaps Questyle is on to something here. All joking aside, the subjective queues here all lead down the same path to quality and push the relative value for the enthusiast consumer to a very comfortable threshold. $1,500 is a lot of money and buyers should expect a decent ROI for their trouble. Relative to the rest of the market the 800R delivers fully on that expectation.

Summary

While the monoblock configuration on the Questyle CMA 800R may be a bit quirky, its singled ended output is one of the best in its price range. Dual SE ¼ headphone jacks are a nice perk to package and its sound quality made up of absolutely top tier stuff. Characterized by a clean, accurate solid stage sound, the 800R’s “Current Mode” amplification doesn’t fail to impress. The energy and liveliness it is able to convey set it apart from the rest of its competition. If the $1,500 price tag is within your range this amplifier is a must audition. One of Audio-Head’s favorites – highly recommended.

http://www.questyleaudio.com/