To start, I would like to thank Andy for inviting me to join the Yulong DA-ART Aquila II tour. There is no affiliation between us. I’m just a normal guy who loves good sound.
PACKAGING
The Aquila II arrived double boxed and well protected. Inside you’ll find the Aquila II cloaked in Styrofoam wrap. Remove the top and you’ll see two compartments. One for the Aquila II and the other for accessories.
The included are a power cord, a USB-A to USB-B cable and a USB-C to USB-B cable. Everything you need to get started playing music.
SPECIFICATIONS
The Yulong DA-ART Aquila II comes equipped with great features. Some of which are trickled downed from its big brother the DA10. Features like its high precision low noise JIC (Jitter and Interface Control) System and a proprietary FPGA solution come directly from the DA10.
The JIC converts the input audio signals into low-jitter, Sbit-stream, then applies FIFO input buffering while synchronizing it with the built-in Femtosecond Oscillators. The system will then pull in and lock the signal via a dual PLL (Phase Lock Loop). The FPGA (Field Programmable Gate Array) will distribute, synchronize the signal and then output a high quality low-jitter I2S bit-stream through FIFO. The JIC also enhances audio performance by optimized data integrity, de-jitter and minimizing digital artifacts before the digital audio signal transmits to the DAC chip.
The Aquila II also features a dual ESS digital processing circuit which allows the user to switch between two different synchronous modes; Synchronous and Asynchronous SRC modes.
Synchronous mode makes use of the FPGA circuitry. The ASRC circuit is bypassed within the ESS9038Pro DAC chip and the original signal is then processed, resampled, and distributed in a different sampling frequency.
Asynchronous SRC mode is optimized by the FPGA and processed by the ESS internal digital circuit. The built-in ASRC function will up-sample the signal to a higher sampling frequency that enhances clarity with refined details.
The difference between the two modes according to Yulong is:
- Synchronous mode: sounds more engaging and musical with an analogue presentation.
- Asynchronous mode: excels on clarity and low-level detail.
Other notable highlights and built-in features are the XMOS XU208 chip handling USB duties. The ESS9038Pro DAC chipset which handles 32Bit/768kHz and DSD512 decoding. All inputs support DoP64 and DoP128. The USB adds additional support for native DSD64/128/256/512. There’s a 99 step digitally controlled analog volume control. A DC coupled class AB amp that delovers up to 4000nW per channel at 32 Ohms. Here’s the full technical specs taken from Yulong’s website:
That about covers the technical aspects and most of the feature set of the Aquila II. One last thing I should mention is the volume wheel doubles as navigation controller. Push it in and you can scroll and choose your input type (USB, AES, optical, and Coaxial), change filters (Choices are Sharp, Slow, and Phase), switch modes (ASRC and Sync) and lastly function ( Head Amp, Pre-Amp, And Pure DAC) on the screen.
BUILD
The Yulong DA-ART Aquila II is rather compact. It’s built on an all-aluminum chassis with a nice size IPS wide angle display. The power supply are independently regulated by two toroidal transformers with low noise regulators. The Yulong DA-ART Aquila II is an all-in-one, fully balanced design. It features a low impedance DAC line output, high current preamp and headphone amplification. What’s missing is the ability to bypass the internal DAC with a DAC of your choosing. So yes, there are no RCA or XLR inputs. This could be a deal breaker for some, but after spending time with the unit the included DAC and its implementation is very, very good.
One the front you have the display window A choice to use a 4.4mm pentaconn, a 6.3mm, or a 4-Pin XLR output. Lastly the multi-function volume controller.
On the rear you have RCA and balanced XLR outputs. A choice between using USB, AES, optical, and coaxial inputs. The power button, fuse enclosure, and power cord terminal.
SOUND
Hifiman HE1000se
Finally, on to the sound. My setup is the iPad Pro, Aquilla II, and various headphones. I started my listening with my Hifiman HEKse’s, sharp filter and ASRC mode. These headphones are easy to drive and sound good out of everything. Listening to them out of the Aqula II was no different. While listening to this combo I made notes like good P.R.A.T., very good bass definition and impact. The treble has very good extension and energy. In ASRC mode there doesn’t seem to be any treble roll off with excellent clarity.
ASRC mode seems to allow full range of the frequency spectrum without abatement. Transients seem faster and the sound is clearer and more details shine through. Switching over to Sync mode seems to tone down the leading-edge transients. The sound is not as sharp or crisp. These differences are very noticeable on the very resolving and transparent HEKse’s.
Moving on, the sound is very balanced with very good midrange presence and resolve. Imaging is good. I can pick out every instrument within their own space. Soundstage is also very good. It’s not the widest or deepest, but the sound is very open and spacious in ASRC mode. In SYNC mode, the sound closes in slightly and becomes more intimate. You do gain more body and a fuller sound as a result of the smaller soundstage. The midrange also benefits from the frequency changes. Voices sound natural and engaging.
Overall, the HEKse and Aquila II makes for a very good pairing.
Dan Clark Audio Ether 2
Next, I did some listening with my Ether 2’s. The Ether 2’s is harder to drive than the HEKse’s. I wanted to see how the Aquila II handles a tougher load. Despite the Ether 2’s having a 16 Ohm impedance I find it takes a beefy amplifier to get the best out of them
What immediately jumped out is the big bass. Listening to Rebelution’s “Bump”, the bass is very deep and hits hard, but it sounds boomy and loose. Bass isn’t as defined as it was on the HEKse’s. The sound is very full and the mids have good body, but overall presentation is very thick sounding. There’s plenty of bass quantity but the quality of bass does take a hit with the Ether 2’s.
The Aquila II is not providing same instrument separation and imaging it did with the HEKse’s. The clarity in the treble remains, which is plus. The treble response with the Ether 2’s is very smooth and detailed. The Ether 2’s can sound dark and overly warm on some headphone amps. That is not the case here.
What the Ether 2 and Aquila II combo excels at is rock and metal. The dense tone and deep bass really adds weight and crunch to guitars. Listening to Slayer’s “Bitter Peace” the guitars really have bite and grit. The bass drums have a very satisfying thump. Cymbal hits have a very nice crashing sound to them. This combo is good with bad recordings and older music. It makes them very listenable.
The Aquila II did struggle a bit with Ether 2’s. Looking at the power numbers of the Aquila II it has more than enough drive to power the Ether 2’s. Yet, I did not find it was the best match for the Ether 2’s It did not provide the same listening experience as it did with HEKse’s. The more I pushed the volume the less control the Aquila II displayed over the Ether 2’s drivers.
Audeze LCD-4Z
After discovering that the Ether 2’s wasn’t the best pairing with the Aquila II, I switch over to another fairly easy to drive headphone, the Audeze LCD-4z’s. My assumptions were proven to be correct in that the Aquila II is a much better performer with easier to drive headphones.
Listening to Parov Stelar’s “Tango Del Fuego”, the LCD-4z’s really took control of the music. Using the sharp filter and ASRC mode, the LCD-4z’s bass was punchy and tight. Georgia Gibbs voice sound grain free, exciting, and natural. Instruments and drums had a very real timbre about them with good space and placement. Treble had great extension and clarity; details could clearly be heard. Nothing really to complain about here with this pairing. Owner’s of the LCD-4z’s might want to take note. If you need a cost-effective amp/DAC and don’t want to get into separate components, the Aquila II fits the bill. Love this pairing.
Sennheiser HD800S
There was one more open headphone I wanted to tryout with the Aquila II and that is my Sennheiser HD800S. My thoughts were since the Aquila II has a very generous bass response that it could offer a nice low-end boost to the HD800S’s. Boy was I right! Listening to Taj Weekes live recording of “We Stand”, the HD800s played the rhythmic bass line with aplomb and relative ease. The bass texture and definition were great. I found myself toe tapping and head bobbing when listening to this pairing.
Listening to this song through the HD800S’s was like being there. I could hear everything. The Aquila II played to the strengths of HD800S. The Aquila II maintained the HD800S’s wide soundstage and filled it up with music. I could hear the reverb in Taj Weekes voice, imaging was fairly accurate and there was a nice sense of atmospheric space, very nice! The sound was crystal clear.
Sticking with the reggae theme, put on Rebelution’s “Bump”. The bass just better. The HD800S’s play the bassline with great energy, impact, and pace. The song was played with such accuracy and depth that I found myself smiling throughout the entire song. Who said the HD800S’s are bass-light?
Sony MDR-Z1R
The last headphone I wanted to tryout is my favorite closed headphone the Sony MDR-Z1R. This also gives me a chance to tryout the Aquila II’s single ended output. The Z1R’s are another easy to drive headphone so this should be a nice pairing. What better way to take advantage of the Aquila II’s strengths than to play Busta Rhymes song “I Know What You Want”. The song begins with a bass frequency sweep, which this combo handled with ease. The entire frequency sweep could be heard down to the lowest of notes without any roll off, impressive!
The Z1R’s bass is seismic, powerful and the Aquila II played it with authority. The Aquila II also shows off the Z1R’s bass response as agile and full ranged. The ZiR’s bass response is other worldly that only but a handful of rivals can match. Vocals were spot on. Busta Rhymes voice sounded full bodied and you hear the raspiness in it. Mariah Carey’s vocals sounded airy and sweet.
The pairing has great P.R.A.T. and is very, very musical. The sound is composed, dynamic, and vivid. The mids shine through even when the low end gets busy. The treble never sounded harsh or exaggerated. Instead, you get an engaging sound that pulls you into the music. I love these headphones and the Aquila II showcases the Z1R’s musicalities. What an outstanding pairing!
Aquilla II vs Flux Labs FA-10
Now it’s time to see how the Aquila II compares to my other amps. Up first is the Flux Labs FA-10. These amps are similar in price, but differ in performance. I must disclose that my FA-10 has been cap modded. I’ve also replaced the fuse with a Hifi Tuning Supreme 3. So, the tuning and performance differs a lot from the stock FA-10. The Hugo 2 will be providing DAC duties to the FA-10 with the iFi Micro iUSB3.0 cleaning up the USB signal.
For this comparison, I’m using a song by Acoustic Alchemy “Mr. Chow” and my Ether 2’s. This song will let me hear how each amp handles acoustic instruments and detail. The FA-10 sounds livelier, more open with better Instrument separation. I can clearly hear the plunking and strumming of the guitar strings a lot clearer on the FA-10. The FA-10 also does a better job at imaging with the add benefit of a wider soundstage. This gives the FA-10 a better sense of space with more depth and insight to the music. The Aquila II does a good job at delivering this music but sits behind the FA-10 in all of these categories with this song.
Changing over to Kendrick Lamar’s “m.A.A.d City” to judge each amp bass prowess was fun. Bass on the FA-10 sounds bigger, tighter, it’s more taunt with better definition. The FA-10 has better control of the drivers and is faster and has a more authoritative delivery. The bass on the Aquila II is just as big, but it’s looser. The bass notes tend to linger around longer and invades the midrange. The Aquila II does have good impact, but recovery is slower so notes can get a little jumbled up in comparison.
The midrange on both amps is forward. Vocals sit nicely in front of the music. Since the FA-10 images better, vocals sound clearer and occupy their own space. This makes the midrange seem slightly congested on the Aquila II.
Both the Aquila II and FA-10 do treble very well. The FA-10 has better treble clarity and extension. This is due largely in part to the cap mod. The cap mod goes a long way in opening up the sound of the FA-10. The upgraded fuse also plays a role in elevating the FA-10 clarity and improving its transient response. Cymbal hits sound splashy on the Aquilla II, while they sound crisper and more focused on the FA-10. The sound is more spacious with more air around the notes as well.
Final say, the Aquila II is good performer. When listening side by side against my modded FA-10 a few things stand out. The Aquila II is not as dynamic, punchy, or as extended at both ends in direct comparison to the FA-10. The FA-10 has more slam, better clarity, faster transient response, better note definition and a meatier presentation. It’s also more powerful and built like a speaker amp. This helps with a lot with driver control and dampening.
CONCLUSION
If the Aquila II had better control of its low end and more transparency to its sound it could a steal of a buy. It’s still a one heck of an all-in-one as you can see from my headphone demo. There’s a lot to like about the Aquila II. It’s a fun, well built, musical amp/DAC with a warmish, musical tone. There’s no denying that the Aquila II has very good bass punch, midrange sound and placement, and treble clarity. What it’s missing is the resolution, musical depth and width, the ability to separate and place instruments like the upper tier amps. The Aquila II also seem to struggle with difficult loads. The music seems to fall apart, bass becomes boomy, and instrument separation is not the best.
One thing that could’ve help boost the performance of the Aquila II is the inclusion of a gain switch. It would’ve made handling of those difficult loads a lot better. It probably would have gotten the performance a lot closer to that of the FA-10 making it an even better buy.
I didn’t want to put the Aquila II up against my reference amp, the Formula S. I didn’t think it would be a fair comparison since it is tied to my Chord TT2/HMS with an OPTO-DX Optical Isolation System before it, and premium cabling throughout. Even without the Powerman, my Formula S betters the FA-10 in almost all categories. Nor did I want to throw in a comparison with the Violectric V281 because it sounds much like my upgraded FA-10. Except it has a slightly pulled back midrange, more resolve, sharper imaging, with more of a upper midrange/lower treble focus. Giving it an airer presentation. The V281 also has a warmer tone. Plus, I didn’t want to extend this review even longer.
The one advantage the Aquila II has over these other amps is it is an all-in-one product. If you’re looking to save money and get very good to great performance, depending on headphone pairing then the Aquila II is a heck of amp. When you put it in perspective, the Aquila II gives you a taste of the high end at a fraction of the cost. It’s only in direct comparisons with top tier amp offerings do you hear its shortcomings.
I enjoyed my time with the Yulong DA-ART Aquila II. If I was just getting started into head-fi this would be a great combo amp to start with. Nice job Yulong!