John Grandberg
Digital audio marches on. The segment is newer, and thus far riper for improvement, compared to the relative maturity seen with amplifiers, turntables, or speakers. Don’t believe me? Let’s take a little trip back in time to 2010.
Have a look around: the D/A converter landscape looks quite different here. Chips of choice come from Wolfson, Analog Devices, Cirrus Logic, or Burr-Brown/Texas Instruments. Upstart firm ESS Labs just launched its highly-advanced Sabre line of DAC chips which are soon to make a big splash, but at present have only appeared in a handful of products. USB is still something of an afterthought – some DACs use low-quality/high-jitter adaptive solutions topping out at 16-bit/48KHz, whilst plenty of others omit USB altogether. DSD playback remains relegated to the physical SACD format, with Mytek’s Stereo192 DSD DAC having been announced but not actually available until Q4 of 2011. Asynchronous USB has just recently become “a thing”, and is only found in a few expensive products from the likes of dCS, Wavelength Audio, and Ayre. These fancy USB inputs top out at 24-bit/96KHz; a mere half of the 192KHz rate possible via SPDIF. Most “serious” audio systems still involve a disc player or transport, and spending less than four digits on a DAC will generally lead to disappointment when heard through a high-end audio system.
Now let’s snap back to the present. ESS Sabre chips dominate. We see custom-coded FPGA conversion used by PS Audio, Chord, Playback Designs, EMM Labs, Exogal, and others. Asynchronous USB is ubiquitous and will routinely handle sample rates up to 384KHz (and often beyond) as well as quad-rate DSD. Optical media is still in use but plenty of folks haven’t touched a disc in years, and a growing number of listeners prefer to stream losslessly from services like Qobuz or Tidal – streaming and file-based playback, in general, has earned a place at the table, even in very expensive audio systems. But my favorite part? High-end DAC advancements have trickled down to reasonably affordable products.
Exhibit A would be the new Aquila II DAC from DA-Art. This US$700 device – relatively modest by high-end audio standards – ticks all the boxes and shows just how far we’ve come in the last decade: top-shelf ESS ES9038 Pro DAC chip running in quad-mono mode; jitter reduction via proprietary FPGA-based signal processing and femtosecond clocking; powerful XMOS-based USB stage capable of handling up to 32-bit/768KHz or DSD512 signals.
These modern features combine with more traditional audiophile aspects not commonly found in the three-digit price range: fully-balanced design; linear power supply with dual shielded transformers and multi-stage voltage regulation; potent headphone amplifier with fully balanced outputs; digitally-controlled analog volume control for driving amplifiers or active speakers directly. Even the large front panel display exceeds expectations. On paper at least, the DA-Art Aquila II is beyond anything we had back in 2010.
Let’s dig deeper.
Design and pedigree
DA-Art is an offshoot of Shenzhen-based Yulong Audio, which has been active in the OEM space and releasing products under their own name for over a decade. In what seems to be the grand tradition of audio companies, Yulong was named after the designer himself – Yulong Zhang. I’ve owned or reviewed a number of Yulong DACs and headphone amplifiers over the years, and have always been impressed by their performance as well as their value. The name Yulong hasn’t proven to be especially catchy for western audiences, which perhaps explains the spin-off to DA-Art. Whether it stands for Digital Audio Artisans or perhaps Digital/Analog Artistry is not made clear. In any case, while this sub-brand itself is new, it does have a strong history behind it, about which you can read more here.
The first thing I notice about the Aquila II is the unique enclosure. While the size – 248mm wide, 210mm deep, and 60mm tall – is par for the course for this segment, the enclosure has interesting flared angles on the sides. This keeps it from being yet another mundane silver or black box sitting on an audio console.
Beyond that, DA-Art’s device has all the expected features, adding up to a rather comprehensive package. The front panel is dominated by a generous IPS display which allows for easy legibility and wide-angle viewing. This display shows us everything we need to know: active input, volume setting, incoming sample rate, and various other adjustments which I’ll discuss shortly. Navigation through these options is easily handled by an intuitive combination of turns and presses to the volume knob. Occupying the middle space between display and volume is a trio of headphone outputs – the standard 6.35mm single-ended jack, plus balanced outputs in 4-pin XLR and 4.4mm formats. Meanwhile, the densely packed rear panel sports RCA and XLR outputs, as well as a quartet of digital inputs consisting of USB, coaxial, optical, and AES/EBU.
Many of the internal highlights have already been mentioned. Worthy of further discussion is the proprietary data marshaling solution which the brand has dubbed JIC (meaning Jitter and Interface Control). Most DACs either use off-the-shelf chips for digital audio reception and asynchronous sample rate conversion or else tap the integrated functionality of the DAC chip itself to handle those functions. In contrast, the JIC system does everything via an FPGA. This means USB and SPDIF signal selection, demodulation, FIFO buffering, femtosecond clock PLL synchronization, and outgoing signal buffering are all done “in-house” before the signal is handed off to the ESS DAC chip for the actual D-to-A conversion. A handy diagram illuminates the process:
Interestingly, we also get the option of using the standard ESS solution rather than JIC. The ES9038 Pro is then responsible for accepting those incoming digital signals, as well as applying its own internal jitter-reduction processing. Users can easily switch back and forth using the menu, where the JIC pathway is dubbed “SYNC” and the stock ESS method called “ASRC”. This is among the very few DACs I’ve ever encountered which can totally bypass the built-in processing of the ESS chip, and it actually leaves us with two fairly distinct ways to listen. But more on that later.
Another option for tweaking comes in the form of selectable digital filters. ESS gives us a variety of options but DA-Art narrows it down to what they feel are the three best choices: slow roll-off linear phase (labeled as SLOW in the menu), fast roll-off linear phase (called SHARP), and fast roll-off minimum phase (labeled PHASE). The differences between SHARP and PHASE are very subtle, and often indistinguishable – as is usually the case with selectable digital filters – yet still useful for adjusting long-term listening trajectory, particularly in combination with the SYNC/ASRC setting. Meanwhile SLOW may be the most drastic impact I’ve heard from a digital filter, casting a somewhat dark shadow over the top end for a relaxed, soft, and very rich presentation. Again, a great option to mix and match to one’s preferences.
The digitally-controlled analog volume control gives 99 steps in 1dB increments. This proves suitable for the vast majority of headphones, from in-ear monitors to big planar magnetic designs. A 2 Ohm output impedance helps minimize frequency response interactions. Line-out gives us a very slightly hotter than average 2.1V maximum output via RCA or 4.2V for XLR, and volume controls can be completely bypassed when running in “Pure DAC” mode. Unfortunately, there is no remote control available, meaning the Aquila II is probably better suited for near-field desktop duty with some active monitors.
The last thing to mention is the USB input, where special care was taken to maximize compatibility with all sorts of devices. DA-Art claims their product pairs not only with the expected Windows and Mac systems but also Linux, iOS, and Android too. With the right cables, I was able to connect my LG G8, an old iPad Air, and even a Samsung Chromebook, in addition to my usual Linux-based music servers and Windows 10 PC. The proper software is required to avoid OS-level resampling, and obviously, there is no guarantee that every device on the market will work. Nonetheless, my experience thus far has been overwhelmingly positive. I wouldn’t necessarily dedicate a smartphone to this task, but using a tablet can be an economical way to add a dedicated transport device to a system – with the sound being surprisingly enjoyable thanks to that proprietary JIC process.
Build
The fit and finish of the DA-Art Aquila II is beyond anything I would expect in the sub-$1000 price range. If placed in a lineup alongside more expensive DACs from Bryston, Benchmark, or the e.One series from Bel Canto (just to choose a few well-known examples), I suspect many observers would peg Aquila II as the priciest of the bunch. Even Mytek’s Brooklyn comes off as somewhat unrefined in comparison (with the exception of its visually intriguing front panel). But seeing is believing – have a look at my pictures and judge DA-Art’s build quality for yourself.
System
The Aquila II was primarily fed by a Cayin iDAP-6 transport (US$799) playing various PCM and DSD files stored on an SD card. A Yulong P18 conditioner (US$379) provided clean power via Audio Art’s Power1 ePlus AC cables. Various headphones including the Kennerton Thekk (€2,680), Meze Empyrean (US$2999), Sennheiser HD650 (US$399), Fostex TH-X00 (US$399), and Ultimate Ears Reference Remastered custom in-ear monitors(US$999) were all brought out to play, as was an older pair of (discontinued) Adam Audio F5 monitors for near-field listening. I contrasted the integrated headphone stage with a few dedicated headphone amplifiers such as Schiit’s Asgard 3 (US$199) and the Drop x THX AAA 789 (US$250), by way of Audio Art IC-3 SE2 interconnects.
Listening
All the high-tech processing in the world won’t mean a thing if the resulting sound isn’t convincing. Thankfully, the Aquila II is just that. It paints a lifelike sonic picture with clarity, speed, and a sense of grace which belies its US$700 asking price. Ten years ago, I would have gladly traveled deep into four-digit price territory for this level of performance.
DA-Art (and parent company Yulong Audio) places an emphasis on designing well-rounded all-in-one products. So that’s how I initially used the Aquila II. Playing Shura’s 2016 retro-glam-pop debut Nothing’s Real via the classic Sennheiser HD650 (with balanced cable), I noted soaring synth melodies laid over a solidly textured foundation. Vocal projection was both extended and well-controlled, and the whole thing felt suitably open considering the limitations of the source material. Switching to the planar magnetic Kennerton Thekk brought a dynamic shift – faster, punchier, with significantly more air up top. I wouldn’t call it spot-lit per se, but there was a pleasing increase in snap and bite to be heard.
This worked magnificently with the Shura release but was somewhat less desirable on Silence Yourself by indie-rock band Savages. The aggressive tonality of tracks like “I Am Here” and “Hit Me” synergize best with smooth/forgiving systems and the DA-Art/Kennerton combo ain’t that. A quick swap to the Meze Empyrean got things back on track, tamping errant high-hat energy and keeping vocal bombast in check without losing the vibrant appeal of the music.
Switching gears to the custom-molded Ultimate Ears Reference Remastered, I was struck by the detail present in Sufjan Stevens’ hauntingly beautiful “John Wayne Gacy”. Here the Aquila II digs deep, capturing the emotive feel of Steven’s vocals and guitar work in a way I typically associate with more expensive gear.
Generally speaking, I’d say DA-Art’s device offers a neutral, authentic presentation, with a certain dose of midrange sweetness to keep it from sounding analytical. Treble is remarkably grain-free, with soundstage suitably open and accurate, and dynamic drive feels plentiful if not quite up to the same level as a good set of separates. The sound is actually quite close to its big brother, the Yulong Audio DA-10 – a device I consider high-value at US$1299.
But allow me to break down a few more specifics.
Using the device in Pure DAC mode (volume control bypassed) with a high-end dedicated headphone amplifier (a Pass Labs HPA-1 in this particular instance) proves the Aquila II DAC portion is of a somewhat higher caliber than the integrated headphone stage. I hear a more convincing sense of bite from Tiger Okoshi’s trumpet, and superior bombast on the John Wick Original Motion Picture Soundtrack. This seems logical as the device is capable of functioning in the role of dedicated DAC, whilst the headphone portion cannot operate alone (there are no analog inputs).
This aspect manifests clearly when moving to more capable headphones. The likes of AudioQuest’s NightHawk, the Meze 99 Neo, or most Grados won’t easily pick up on the difference, whilst more discerning Audeze, Sennheiser, and Focal models absolutely will. The Aquila II is thus quite versatile – it gives us a pleasing all-in-one performance now, with the ability to upgrade amplification down the road. Alternatively, we could offset the DA-Art’s ‘neutral’ integrated amplifier with something like a Feliks Audio Echo for a vastly different presentation. Note that balanced mode is the way to go when tapping the integrated headphone section; it feels more robust and dynamic than single-ended (which is still quite capable if comparatively a bit bland).
Meanwhile, that integrated headphone stage can hold its own when sat next to the reasonably priced competition. Schiit’s excellent Asgard 3 sounds faster and gives notes a more forceful sense of dynamic “grunt”, whilst the Aquila II output stage offers a sweeter, more liquid-sounding midrange. Likewise, the Drop THX 789 involves a bit of a trade-off: superior treble clarity with a blacker background in exchange for somewhat constricted staging and a wiry character. These third-party solutions offer plenty of appeal yet the Aquila II’s integrated headphone output keeps pace.
DA-Art also gives us subtle tuning choices. Cycling through digital filters is often imperceptible, yet the difference between the integrated ESS processing (ASYNC mode) and the proprietary JIC system (SYNC mode) is more pronounced. I hear ASYNC as having a somewhat brighter and textbook “flat” presentation, which at times is desirable given the right combination of music and headphones. The flip side is that it can feel slightly brittle and edgy at times. Combining it with the SLOW filter helps in some cases. Direct comparison with SYNC mode reveals DA-Art’s JIC system to be more relaxed and nuanced, with midrange notes being particularly more rounded and sweet – a pleasing result in most situations. JIC also has a broader, almost zoomed-out effect, while the ASYNC mode is more up close and direct. Again, nice to have different options for various situations, but I mostly prefer JIC, combined with the PHASE digital filter for the best mixture of richness and detail.
Another significant benefit of the JIC system is heard when pairing the Aquila II with modest digital transports. While both digital pathways can soar with a quality spinner or streamer in the chain, JIC does not regress much when fed via more pedestrian sources. I broke out the most basic transports I could find: USB from an ancient MacBook Air; a cheap Blu-Ray player’s coaxial; the Asustor NAS’s Toslink. In all cases, the Aquila II gave results that weren’t far off from my usual high-end sources. It seems DA-Art has indeed mastered the “art” of jitter busting and noise reduction.
Comparison
The most appropriate competition I have on hand right now is the diminutive Mytek Liberty. The littlest Mytek is known for offering plentiful bang-for-buck, and – when augmented by an aftermarket PSU – can arguably compete with its upscale Brooklyn sibling. But even in stock form, the Liberty is what I consider a safe recommendation in the sub-US$1000 DAC market.
Comparing the devices as all-in-one units with the excellent Campfire Audio Cascade headphones (review coming soon), I learned two things. First, the Aquila II can be made to sound remarkably Liberty-like in certain configurations. Choosing the ASRC option combined with the FAST filter gives DA-Art’s machine a brilliant sense of clarity, just as described by Phil Wright in his Liberty review. I really did have a tough time separating the two, which is impressive considering the nearly three hundred US dollar advantage held by Aquila II.
The second thing I learned was that when switching to my preferred settings, I found the Aquila II to completely outpace the otherwise enjoyable Liberty. Bigger, bolder dynamics, richer tone colors, and a greater sense of ease to the presentation made for increased listening enjoyment across all genres of music. I found myself wishing I could swap the Liberty out for a Brooklyn+, as that seemed like the more appropriate challenger regardless of its price difference. Alas, while I’ve heard the Brooklyn+ in my system on many occasions, I couldn’t get my hands on one in time for a direct comparison.
Considering the imminent launch of Mytek’s Liberty DAC II, it may be unfair to pit the new Aquila II against an outgoing Mytek model. Nonetheless, the Liberty is a known quantity for many, whilst DA-Art is a relatively obscure newcomer. As such it feels like a worthwhile comparison to make – I did not expect the Aquila II to emerge as the victor, but that was the clear result of my listening. Augmenting Liberty with an external linear power supply can certainly help close the gap, but also extends DA-Art’s already considerable advantage in terms of pricing.
Conclusions
Balance – it’s the word that most vividly comes to mind when trying to sum up DA-Art’s superb Aquila II DAC / headphone amplifier. True, the design itself is fully balanced, as is the integrated headphone amplifier. But more to the point, the device strikes an excellent balance of features, build quality, and engaging sonics, for a price that stops well short of four-digit territory. A decade ago, I wouldn’t have predicted such a thing. And yet here we are.
Further information: DA-Art
