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Headphone amplifier. All commercial reading materials on the Vaughan describe it as a 32/384 digital-to-analog converter. There is no mention however of as essential a functional component as the headphone amplifier. Yet after disassembling the unit I saw that it was no after-thought addition but a full-fledged circuit based on discrete output transistors assembled on a separate large PCB. The only component this board shares with the main circuit is the digital volume control. Hence I approached this review chapter with curiosity and heard how the 6.3mm output is a decent solution with a very detailed dynamic sound. In this application I simply missed bass and midrange saturation so my audition focused on the AKG K701 and HiFiMan HE-300 headphones. The Sennheiser HD800 emphasized the advantages heard earlier as well as flat frequency response but also quickly revealed the weakness of the headphone port – lack of dry muscular bass and leanness in the midrange. This feature/function isn't on par with the Vaughan's perfect converter. Ditto preamp (amp-direct) mode which I'd treat as a useful interim rather than final solution.


Conclusion. For any declared flagship product manufacturers always throw behind it the fullness of their know-how and experience. After all their reputation is on the line. If the sound doesn't meet a customer's expectation, excuses like "they specialize in mainstream electronics and high-end is just a side project for fun" won’t do. It could well ruin a company's image. I've already seen a few times how that can end – by vacating the market place altogether. After auditioning the Vaughan, learning about its technical objectives and how they were implemented, I can’t help but come to the conclusion that these people know what a high-resolution audio file is and are fully capable of extracting it from their USB input. For while I haven’t yet heard this device in its presumably top form—with 32-bit/384kHz files for which I lack gear that provides such a signal even though I do have some DXD recordings—one already hears with files ripped from ordinary CDs that it is exceptional and significantly better than the analog line-out from a dedicated CD transport or average-quality file player even if the latter runs 24/192 files.

I've heard something like it only a few times before like with the Musica Ibuki Series Sekigahara Japan DAC. This rarity explains why this experience was so moving now. The Vaughan shows what computer audio is capable of if done properly. It becomes a completely new experience. It is no coincidence that the Japanese go crazy over turntables, SACD players and computer audio including stationary file players. Over years of experience with products from their hands I've learnt that I can’t ignore even their most bizarre ideas because sooner or later I mature enough to understand them. The folks from M2Tech probably realized it much earlier than others: USB is the gateway to a whole new world and they just opened it wide.


Design. The Vaughan is a digital-to-analog converter with integral digital volume control to transform into a potential preamp and headphone amp. The unit is very large, larger even than the Mark Levinson N°.512 SACD player which it replaced on an Acoustic Revive RAF-48H anti-vibration platform. The enclosure is made of thick aluminum panels. The curved front panel of perforated metal conceals a very large red dot-matrix display. On the right side sits a large chromed volume knob and 6.3mm headphone jack. On the left are two buttons. One activates the menu and the knob then navigates through it, the other exits the menu or enables standby. If we want to completely disconnect from the mains we use a mechanical switch located next to the IEC power inlet on the rear. The display can be dimmed in six steps or set to automatic mode to light up only if we change a setting, for example alter volume. I think it could remain lit for a bit longer. The display indicates selected input and the sampling frequency of the input signal. Turning the volume knob shows the current level in dB or relative. The menu also displays battery level, channel balance and absolute phase. Missing is indication of bit depth.

The rear is packed with 13 digital inputs: 1 x USB B, 1 x I²S on RJ45, 2 x S/PDIF coax, 2 x S/PDIF 75Ω BNC, 2 x AES/EBU XLR, 2 x Toslink, 2 x ST. Apart from Toslink (24/96 kHz), all others accept 24/192 signal. The twinned sockets can also be used in a dual-cable setup to then transfer up to 384kHz (192kHz for Toslink). Only I²S and USB handle 32/384 via single cable. An external reference clock may be slaved to a BNC input. The I²S connector is galvanically isolated, the other inputs sport matching transformers. Analog outputs are on XLR and RCA. All socketry appears to be very solid.

The Vaughan is actually several M2Tech devices in a single case even though it's not a combo kit. All circuit and sub systems were custom designed and built for this model. In the center well removed from other circuits sits a switch-mode power supply inside a perforated metal cage. It contains a mains filter to prevent ultrasonic noise from being leaked back into the mains which could adversely affect other components. This power supply doesn't communicate with or connect to any audio circuit but merely charges the LiPo battery in the neighbouring compartment.

That's because the Vaughan is fully battery-operated. Its main circuit mounts to a large frontal PCB. The lower row of sockets solder directly to it, the upper row uses an auxiliary board. I'd thus use the former just to be sure. The signal path from the buffered inputs first encounters a Burr Brown DIX 41921 digital receiver from where it is sent to a powerful Xilinx Spartan-6 DSP chip which implements in-house coded upsampling and digital filtering firmware. It seems that here also resides the digital volume control. As we read in the company materials, the input signal is processed with 64-bit precision so there is no concern about resolution decimation. The next step is the actual D/A conversion via eight Burr-Brown PCM1975 stereo DACs hence eight converters per channel. Such paralleling is used successfully by many companies like Accuphase and T+A. It helps to minimize quantization errors, noise and distortion. Interestingly here this arrangement has been maximized since the ICs don't connect to each other. Each is a complete stereo system with its own I/V conversion. In the output stage we find IT OPA2211 opamps. The entire audio circuit is surface mounted featuring quality passive parts like Wima polypropylene capacitors and resembles what we have seen in the Young simply multiplied.

The headphone amplifier mounts on a separate board attached to the rear panel. There is a quad-chip Analog Devices AD8674 on its input and the output is based on a pair of transistors in push-pull mode. The transistors mount to an aluminum plate which in turn bolts to the rear panel. It is worth mentioning the beautifully designed clock circuits, one each for the 44.1 and 48kHz sampling-frequency families and the DSP chip on the USB input which implements the custom asynchronous 32/384 reception.
opinia @ highfidelity.pl
M2Tech website