YULONG Aquila II

Slim1970

Headphoneus Supremus
Yulong DA-ART Aquila II, mid-fi at its best
Pros: Good sound
Punchy bass
Nice forward midrange
Good treble extension and clarity
Cons: Lack of a gain switch
No RCA or XLR inputs for external sources
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.

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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.

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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:

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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.

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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.

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SOUND

Hifiman HE1000se


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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

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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

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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

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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

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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

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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.

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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!
InstantSilence
InstantSilence
A sweet read! As always, the reliable reviews from Slim are a joy to read!
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shenzhenaudio
shenzhenaudio
Nice review! YuLong AquilaII needs to be promoted, it's really nice desktop.
Slim1970
Slim1970
Thanks @shenzhenaudio. I agree it’s a very nice amp. I really enjoyed my time with it!

ngoshawk

Headphoneus Supremus
Yulong DA-Art Aquila II ($640-700): A canted box, with good sound.
Pros: Affordable
Clean sounding
Decent sized for desktop
Multiple set up options
Cons: No real personality, as in fairly neutral (which can be good).
Maybe not enough power for some?...
Yulong DA-Art Aquila II ($640-700): A canted box, with good sound.

Aquila page:


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DA-ART Aquila II is our latest premium All-in-One DAC/Amp/Pre for Personal Audio application. It incurred numerous technologies from our Reference product DA10 including the high precision low noise JIC (Jitter and Interface Control) System, our proprietary FPGA solution to enhance audio performance by optimized data integrity, de-jitter and minimized digital artifact before the digital audio signal transmits to the DAC chip.

The Aquila II measures exceptional well, and it also sounds incredibly resolving and realistic. It is designed around the ESS flagship ES9038Pro 32-bit DAC chipset offering768kHz and DSD512 decoding capability. It takes advantage of the new ESS design and facilitates a dual digital processing circuit offering two distinctive synchronous modes. The analog audio circuit has incorporated a high precision analogue volume control to make sure the pre-amplifier and headphone amplifier output preserve every bit of resolution and dynamic even at low volume level.

Having been part and parcel to many of Andy’s tours, I jumped at the opportunity to review the Aquila II. Andy has never led me wrong in an item, and my pocketbook is on a first name basis with him as a result... For good or bad (always good), I have many of the items from previous tours. As always, I would not purchase said items were they not pleasing to me and perform admirably. All that was asked is an honest review of the product. The unit will then be shipped to the next. I was even lucky enough to have a couple of other wares with which to use for comparative purposes. As always, I thank Andy and I thank Yulong for sending the Aquila II on tour.

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Interesting info:

The key features are:

● Proprietary high precision low tolerance YULONG JIC (Jitter and Interface Control) System:
o Optimize data integrity and enhance digital signal quality.
o De-jitter and minimize digital artifact.
● Outstanding digital audio capability:
o Design around ES9038Pro DAC chipset with industry-leading 32Bit/768kHz and DSD512 decoding
o Widely recognized XMOS XU208 solution with customized (with license) Thesycon driver to enhance sound quality and stability.
o All inputs interfaces support DoP64 and DoP128, USB input interface supports Native DSD64/

128/256/512 additionally.

o Choices of 3 digital filters to fine tune your system for different music genres and personal preference.
● Custom developed dual digital processing circuit offers unique digital audio options:
o Synchronous mode: sounds more engaging and musical with an analogue presentation.
o Asynchronous mode: excels on clarity and low-level detail.
● State-of-the-art analogue implementation:
o 99 steps digitally controlled an analogue volume for Preamp and headphone output.
o DC coupled Class AB amplification, delivers up to 4000mW per channel at 32ohm.
o Outstanding headphone performance specially optimized for low impedance headphones, ensure low distortion and outstanding handling capability even at 160hm loading.
● All-in-one design with comprehensive connectivity:
o Fully balanced design, low impedance DAC line output, high current preamp and headphone amplification.
o USB Audio supports MS Windows, macOS, Linux.
o Special attention to enhance support to Android and iOS mobile and tablet devices.
● Multi-stage independently regulated power supply from two toroidal transformers with low noise regulators.
● Intuitive control through single high precision probably damped volume knob.
● Seamless, compact and sleek aluminum chassis with large IPS wide angle display, supported by unique suspension feet.



Specs:

USB AudioPCM: upto 32Bit/768kHz
DSD: DoP64, DoP128, Native DSD64/128/256/512
Synchronous Mode
(Coaxial, AES, Optical)
PCM: upto 24Bit/384kHz
DSD: DoP64 and DoP128
Asynchronous Mode
(Coaxial, AES, Optical)
PCM: upto 24Bit/192kHz
DSD: DoP64
Power Rating (Headphone)(Measured at THD+N< 0.001%)
Single-ended (6.35mm)32Ω64Ω 150Ω300Ω600Ω
1600mW870mW370mW180mW90mW
Balanced (XLR4 and 4.4mm)32Ω64Ω 150Ω300Ω600Ω
4000mW3000mW1500mW750mW375mW
Frequency Response20-30KHz (±0.15dB)
THD+N0.00025%. (1kHz, 20Hz-20kHz, A-Weighted)
Dynamic Range: 125dB (20Hz-20kHz, A-Weighted)
SNR-130dB (20Hz-20kHz, A-Weighted)
Crosstalk < -120dB
Output Impedance~2Ω (XLR4, 4.4mm and 6.35mm)
Output Level (Line Out)Single-ended (RCA) 2.1V
Balanced (XLR) 4.2V
Power consumption<30W
Dimension248*210*60mm (LxDxH)
Weight4Kg


Gear Used/Compared:

XDuoo TA-30 ($710)
Little Dot mk3 se ($429)

Cayin N6 mk2
Shanling M6 Pro
MacBook Pro

ZMF Eikon
Audeze LCD-3
Dunu Luna
Verum Audio Verum 1
VModa M-100 Master (as part of that review)
Others as warranted


Songlist:

Joey Alexander-Warna album and others
Mark Knopfler-Laughs And Jokes And Drinks And Smokes
Santana w/ Mana- Corazon Espinado
twenty one pilots album, Trench
Tedeschi Trucks Band
Big Head Todd & The Monsters-Beautiful World
Mark Knopfler-Down The Road Wherever
Elton John-yep, still good, still cool
Tidal MQA


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Unboxing:

Coming in a box, the Yulong was taken out of said box. Wrapped in a plastic blanket for protection against the cold flight from overseas, the Yulong suffered no wear. Included besides the power cord were two connecting cords (one is the optional cord for using an Android Smartphone) to keep the power cord company on that long, cold flight. Not wanting to show off, those shy cables were a white USB-C cord and a subdued black USB-A cord. All survived the cold, dark flight and were ready to go upon unboxing. An instruction manual came as well, so the feeding options could be easily understood, for the Yulong was indeed hungry after the flight.

Warming the unit to acclimate it to the near-plains state temperature (its figg’n cold now, go figure...), I finished another review and even called upon the Aquila for comparative purposes.


Controls/build/etc:

Often, I eschew having a solitary control knob, for I am in want of many switches clearly laid out, so I do not go into full-on “lost pilot” mode. But anyone that owns a newer car will understand that having a single control knob has it benefits and carries over into the Yulong easily. Since we ourselves own cars with said solitary knobs, even I could discern the workings of the unit.

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Coming with an angular top, which slants toward the center like a Morton building on a farm, the Yulong looks the part and separates from those silly plain black boxes. The unit came in an icy-silvery-white color not unlike some recent new cars. It really was not from the frigid flight... The knob also doubles as the volume knob nicely.

A single digital display with a tactfully less-than-spotlight bright shows everything you need from what input you are using to the decoding level on the top row; followed by filter rate, synchronous/asynchronous mode, how the unit is used (head amp, Pre-amp, DAC); and volume in -dB’s. Thankfully when switching to DAC mode, a large warming of MAX comes up to denote the volume will be at maximum level. A nice warning. In the middle (just like the MAX) the display shows the sampling rate.

With three headphone inputs of 4.4 Pentaconn, 6.35se, and XLR-bal between the control knob and display, the front is complete. Clean and straightforward.

The back holds the connectivity aspects with (L to R) the RCA connection, analog XLR, coaxial and optical (on top of each other), AES/EBU, and USB. The on/off switch is close to the power plus, which also contains a fuse to prevent overload. No wasted space, and efficiently laid out so you can have many sources connected at once. Switching between is as easy as pushing the control knob on the front. Simple and thoughtful, this is a good start.

As for the build of the unit itself, the Aquila II is well built with no obvious mismatching’s or unevenness of paint and the unit even has a good tactile feel with which to help you grip the unit should you want to move it. Nicely done.


Insides:

From the above stats you get the idea this is a very technical unit, which seems to be completely new in design. It isn’t and builds upon previous Yulong models to raise performance level. Coming with a Sabre ES9038Pro DAC chipset, the unit is off to a good start. From the diagram below, you can discern the inner workings for yourself. I bow to those who might follow with regard to the technical of said innards. Suffice to say I am on a string of ES9038 chips and appreciate how clean they have been. My current favorite uses that chipset, and it is the finest iteration of said chip I have heard. Yes, even I can hear this difference when combined with the complimentary objects within. But as stated, I shall let others discuss the finer points of the other items. I avail to state that the Sabre chip is good. Really, really good.

I will add the following from the excellent Headfonics review as reference material regarding the three chosen filter options, which states that even though the Sabre chip has up to 8 filter options, Yulong chose to only include the three listed below as they showed the most sound signature changes (https://headfonics.com/yulong-da-art-aquila-ii-review/):

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Phase:

This minimizes the pre-ringing effect and the default filter setting; this is the equivalent to the minimum phase fast roll-off filter in the main ESS description.


Sharp:

This represents a flat response and is recommended for general purpose use. YULONG describes this filter as being suitable for most genres and is the equivalent to a fast roll-off or linear phase filter in the main ESS description.


Slow:

A gently roll-off on the high frequency. This is recommended for music that benefits from a smoother presentation and is the equivalent of a slow roll-off, linear phase filter in the main ESS description.

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Sound:

As others have stated in various reviews, the pure sound of an amp of such sort is hard to gauge because of so many outlying factors. As I tell my science kiddos, when we investigate a lab, we MUST keep all extraneous factors out and look at a single independent variable. Otherwise, the results are too open for misinterpretation. Sound science looks at one change at a time, and this follows here as well. Using my MBP and Tidal MQA first, I varied headphones to discern differences in sound. @Wiljen was kind enough to let me know that I should try my harder to drive headphones first, and this is where the Aquila II would start to shine.

Even though the Yulong has one “switch” on the front, that does not mean it comes short-featured. Running between “ASRC” and “sync” mode there are discernable difference. Sync mode seems a bit richer of tone, while the ASRC seems more clinical. Succinct and with a purpose would be a good way to describe ASRC. Tighter with more urgency would also work.

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My hardest to drive headphones, the LCD-3 come into play here as do my Beyerdynamic T1 V2 and ZMF Eikon; none of which are really that hard to drive. But I hope to get a sense of how the Yulong works.

What you can start with is that the Yulong presents a crisp, clean sound, without warmth. Neutral comes to mind and using the filter changes can move that one way or the other. This comes through in the ASRC mode with most songs. David Bowie’s vocals are crisp and clean, with a bit of that perfect upper mid song he has coming through. On sync mode there is a bit of “soul,” with a deeper richer tonality. I cannot say what my preference would be. I found myself leaving the switched mode both ways on different days, without a care as to which one was on.

Sync mode did drop the upper end noticeably to me, toning down an already mellow sound from my Eikon. Not bad mind you, but on a song such as China Girl, which is such a sweet-sounding upbeat song, I did prefer ASRC mode, especially when SRV’s guitar licks took over. Superb instrumentation came about as a result of the pairing.

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Switching to my LCD-3’s, the sound with a slow filter and ASRC was deep and rich, with that Audeze bass coming through nicely. The mids did seem to suffer a bit, like they were held back, though. Switching to the “phase” filter alleviated this a bit, but I think it was the treatment from the LCD-3 that caused this “discrepancy.”


IEM’s

I did notice that with sensitive IEM’s, the background was not black, but with an audible hiss, until the song started playing. This is a sensitive amp and as such suffered a bit with those types of IEM’s. Also, this is quite a powerful amp and as such use with caution with your sensitive IEM’s. I found with the FiR Audio M4/M5 the sound was excellent, but I needed to turn the volume down. No matter, for the sound was still very good. Regardless of listening device, you can make the Yulong as tight and controlled or somewhat mellow to your near-desires. Most quality amps of today have that capability anyway, but the Yulong seemed to bring out those differences a bit more so. The same hiss was heard on the Dunu SA-6 as well, but again this did not hinder the sound capabilities once playing started.

Plugging in my Legend X worked well, as I expected it would. Having that darker, richness to it, and the bass of God’s, the LX did not disappoint. Easy to drive as well, the power behind the Aquila II was easily utilized by the LX. Quality abounds with the pairing and so with other pairings presented and noted here.

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Source comparison:

Yulong DA-Art Aquila II ($700) v XDuoo TA-30 ($710):

Running an excellent pair of Mullard tubes I had switched in for an already thoroughly competent set of RCA tubes, the TA-30 is a monster when it comes to power. Hearkening back to the HEDDphone I had a while back, the Ta-30 drove them silly powerful. I really did not miss the lack of a balanced output with the TA-30, and still do not to be honest. I use the TA-30 for those occasions when I just want to jam out without cause for whether it has the “latest, greatest” connections. That said, source connectivity with the XDuoo is amongst the very best I have running the full gamut from optical, to BT to coax and everything in between. It is crazy-connection time.

The TA-30 is almost too much for what it is. You really need a hard to drive headphone such as the HEDDphone to get the best out of both. And while I have used my LX out of it, I would not recommend the XDuoo for IEM’s, it’s just too powerful. You do get more filter options as well as BT. If connectivity is what you crave, it is pretty much a wash, but if you want to fine tune your sound more, the TA-30 one ups the Yulong. That said, there is sound reasoning behind Yulong only including three filter choices and that makes sense. With the ASRC/sync mode and three filters you still get six choices, and hence Yulong focused in that direction instead of multiple filters...


Yulong DA-Art Aquila II ($700) v Little Dot mk3 se ($429):

Having the LD mk3se on hand was indeed a very nice treat. Will graciously allowed me to have it (and for longer than I should have...), but I do believe they could be compared even though they do things quite differently. While not really a fair comparison as I was using the extraordinary Tesla tubes Will included, this makes for a valid one nonetheless because it shows what can be done for near the same price.

The LD’s bass through the Tesla tubes is really perfect when coming through the LCD-3. A nice rich tone came from down below, with a validity that warranted respect. I will add that through the Shanling M6 Pro there was also a rich vibrant tone as well. Running completely balanced, I was afforded a nice vibrant texture to the sound. Almost a bit too bright, but I thoroughly enjoyed the sound.


Finale (longer):

I usually go into more details above, but this was a tougher one to do. As such, the finale will cover what I felt could not be covered above.

Reviewing amps and DACs is hard for me, I admit it. this is probable where my high-end hearing loss suffers the most. I simply cannot discern the finer attributes of the differences. What others hear easily, I struggle to hear, then struggle more to comprehend. But with that comes a certain focus, carried over from my birdwatching and surveying days. If I heard a bird song that was different from what I had already heard, then I knew it was something different than my “normal” route birds. I once heard a Yellow-billed Cuckoo (Coccyzus americanus) off in the distance, which was somewhat rare where we were. My partners did not hear it and essentially blew me off. That is until it flew within about 75 yards of our station...from that point forward the other two gents paid close attention when I mentioned I heard something out of place for they knew that their excellent hearing benefitted in placing the bird. Teamwork.

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And here is where I think I can discern what makes the Yulong “different.” It is affordable. It is new. It has heritage of its ancestors. It has what you need. There are connections a plenty. You get an xlr connection and a 4.4bal connection. You get ease of use (one button controls all). You get enough power to drive all but your hardest headphones to levels deserving of them. And as many more learned than me state time and time again, to get the best out of your expensive cans you need power! Enough to drive it properly, but without killing your ears. The Yulong does that and does it well. You get to listen to clear, crisp sound, that can be tailored at the move of a switch. Quick and easy, you change the sound in which you listen. No fuss, no mucking about save that it does not come with a remote (would be nice to have...).

But, and here it comes, there are others that can do all of the above for near the same price. You can get similar performance from other manufacturers and get similar performance from manufacturers who’s wares cost 2x more as well. And this is where it also gets interesting. We are faced with a plethora of listening devices and why not a plethora of amplification devices as well? The Yulong fills into a niche of mid-fi quite nicely and performs admirably against the competition. You get fully balanced. You get two options in which to listen with both being balanced as well. You get a powerful semi-tunable DAC/amp that can function easily in most systems, without fuss. While not necessarily presenting as much character as some (such as the XDuoo TA-30 mentioned above), you get a thoroughly competent, clean sound that provides you with options in which to listen.

I cannot find too many faults in the Yulong save that it presents a near-neutral sound. Mind you, that is not a fault to many, and you can tailor that a bit with the ASRC/sync options, but is it up to the DAC/amp to flavor your sound too much? To give you that luscious deep-richness you crave? Or is its job to provide the listening platform that carries the sound across cleanly to your listening devices? Those hard to drive headphones will not suffer from that lack of “character” the Aquila II may have. In fact, it may benefit allowing you to really focus on the headphone listening pleasure instead. The Yulong DA-Art Aquila II just gets out of the way allowing the listener to experience the music and the headphone you are using. And sometimes isn’t that the point?

I thank Yulong and Andy Kong for another stellar tour presentation. I am humbled to be part of the tour and will pack with care the Yulong so that the next lucky person may experience it. It is worth a listen and a good comparison to what you have.

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szore
szore
Reading an amp review, suddenly we are bird watching! :hugging:
ngoshawk
ngoshawk
Haha, I try. I was a bird biologist in another life. :relaxed:
senorx12562
senorx12562
Now the handle makes a little more sense.

Wiljen

Headphoneus Supremus
YULONG Aquila II - A budget Da10
Pros: Good power without a lot of heat build up, very good DAC performance, several filters and options to tune the sound.
Cons: Not a great pairing with super sensitive iems, no gain control, cannot be used as amp from another DAC.
Yulong-aquila2-front-800x445.jpg


disclaimer: The Aquila ii was sent as part of a tour for purposes of review and was sent on to the next reviewer immediately after completion of this review. I have no financial interest in YULONG or any of its vendors, nor did I receive any compensation for reviewing it. If you have an interest in purchasing any of the YULONG products, see their website. For the record, my capitalization of the name is done for the reason that YULONG represents the brand while YuLong is the person who founded the brand so I didn’t simply forget to clear caps-lock.


Unboxing / Packaging:

Unboxing is not much of an event as the Aquila II (Aq2 hereafter) is clearly packaged for transport and not for retail sale. Brown cardboard with the YULONG Name, the model, and some minimal graphics are what greets the user when you open the shipping package. Inside we have a closed cell foam tray with the Aquila II in the main compartment and the cables (USB-A to USB-B, USB-C to USB-B, and power cable).


Build/Fit:

The Aq2 is offered in three colors of anodized aluminum shell (Red, Black, and Silver) with the tour unit being the black version. Weight is roughly 10 lbs and size is roughly 10 x 8.25 x 2.5 inches. Front and rear faces are vertical while sides have a mild slope inward from bottom to top resulting in a trapezoid shape. The front face from left to right has a sizeable display screen (roughly 3 x 1.75 inches), followed by a 4.4mm balanced port, a 6.3mm single ended port, an XLR balanced port and lastly the volume/Selector knob at far right. The rear face from left to right starts with RCA outputs followed by a pair of XLR outputs, next up are the inputs with coaxial over optical first, AES/EBU next and finally USB. To the far right is the power switch, fuse, and c13 female power connector all built into a single unit. The Aq2 has an auto-sensing 110/240V power input so changing cables should be all that is required for use in different environments. The first thing I check on a product at this price point is the uniformity of anodizing across all parts and the fit of those parts. The Aq2 doesn’t disappoint with the volume knob being a near perfect match for the the main shell and the rear face equally well fitted and anodized. The next thing I look at is how tightly the connectors are mated to the shell and here again they are well done with no play, gaps, glue, or wobble to any of the connections and the female connectors are well centered in the ports . I do appreciate the large countersinks around the single ended connectors on the front as there is so much variation in style and size of the male connectors. This design accommodates a very wide range of jacks without need for altering either the unit or the jack. When run for considerable time, the unit is warm to the touch but does not heat up considerably so would be at home in an audio cabinet or small space unlike some other small DAC/Amps that need a good bit of breathing room to prevent heat buildup. Overall, its a good looking unit with a unique style that breaks away from the standard rectangular black box. Were I to purchase the unit, I think I’d go red.

The Aq2 can be used as a DAC/Headphone Amp or DAC/Pre-amp. It has the ability to utilize a very wide range of sources including MAC and Windows PCs, Android devices, IOS devices, and anything that support coaxial, Optical or AES output. The Mobile mode is an interesting feature and I found the Aquila behaved well with a Motorola and LG Android phone as well as a Samsung tablet, two generations of I-pad and an aging Iphone 8 that I need to trade in for a new one. Perhaps oddly, there is no bluetooth input and instead the USB is optimized to support IOS and Android devices. Another thing to note is there is no option to bypass the DAC and only use the Aq2 as a headphone amp so unlike some others in the market this is strictly a combo device of either pre-amp or headphone amp and DAC.

Yulong-aquila2-front.jpgYulong-aquila2-rear.jpg



Internals:

Now for the good parts, what makes this thing tick. Starting with the power supply, the Aq2 incorporates a multi-stage linear power supply using dual toroidal transformers. These are smaller than the single used in the D10, but are double shielded to keep things clean internally. Inputs are handled by an XMOS XU208 stage followed by a custom FPGA that YULONG calls the JIC or Jitter and interfacing controller. This provides clock sync, jitter correction and the fifo buffer. From there, the signal is fed to an ES9038Pro dac chip for conversion to analog. One thing to note is that the filters on the 9038 are exposed to the end user. Options are Phase (min phase fast roll-off), Sharp (linear phase fast roll-off) and Slow (linear phase slow roll-off). Another feature implemented in the Aquila that first appeared in the D10 is what YULONG calls the digital processing circuit. This feature allows the end user to choose whether to use the ASRC circuit in the 9038 or bypass it and use the FPGA to provide this function instead. The digital synchronous mode (bypass) provides a slight tuning change without the “ESS Hump” but sounds slightly less lean and analytical. The Async mode (use 9038 ASRC) has the familiar ESS sound with its analytical tilt and slightly cool tuning. I appreciate the option to choose between these on the front menu as I found times I appreciated both. One thing to be aware of is that the Sync mode (bypass) allows coax, optical and AES inputs to stretch a bit more with maximums of 24/384 PCM and DSD128 (DoP) while the Async mode (9038) is limited to 24/192 PM and DSD64 (DoP). Amplification is handled by a single class A/B circuit using a 99 step digitally controlled analog volume control but no gain adjustments. This is the biggest departure from the earlier Da10 and the big reason the Aq2 costs roughly half the asking price of the Da10. The output numbers for the Aquila are higher than those of the Da10 but keep in mind the Da10 is a pure class A amp while the Aq2 is an AB. The single ended output is rated at 1.6 Watts into a 32Ω load while the balanced outputs offer 4 Watts into the same load. Also be aware that the output impedance is a bit higher than some at 2Ω sp use with low impedance in-ears may show some impedance mismatch. Pre-amp outputs are listed as 2.1V for the RCA and 4.2V for the XLR.

Yulong-aquila2-specs.jpgYulong-aquila2-internals.jpg




Controls:

Controls on the Aq2 are handled by the display screen at far left, and the multi-function knob at right. Font size on the display is much better than on some like the Burson Swing/Conductor and UI is easier to navigate than many partially due to the limited menu of options to pick from. Pressing the knob in once allows selection of input with the corresponding display icon showing top-center. Pressing the button in twice takes the user to filter, three times to mode (Sync or ASRC), and 4 times to function (DAC/pre-amp/head-amp). Once an option is selected rotating the knob scrolls through the choices and pressing the knob again sets the desired option. If there is a gripe, when an option is highlighted but not selected yet, the display inverts color to show the user which option is being adjusted and unfortunately this same indicator can make the text hard to read. Thankfully there are few enough options that selecting it and returning the display to normal allows for a quick check that you have made the right selection and correction is simple if for some reason you got the wrong one.

Aq2-display.jpg


Sound:

Filters:
I found I preferred the Sharp filter which YULONG describes as suitable for most genres and yet does not set as the default instead making Phase the default option. Although simple to change, I would have liked to see the Sharp option as the default as it has the greatest utility in my thoughts. Slow smooths the top end a bit more than I care for, and Phase while nearly as good as Sharp to me loses a little in transient response.

As for modes, these make a much bigger difference and are likely to be quite polarizing as some will undoubtedly strongly like or dislike one or the other. The ASRC mode is fairly typical of a well implemented ESS chip with a near neutral signature with a mildly enthusiastic treble response. I don’t think treble is vastly exaggerated and it may even be that what I hear as a lift here is more of a drop on the Sync side comparatively. ASRC has a bit more mid weight and they seem slightly more forward and the treble energy is higher compared to the Sync mode. The advantages of Sync are treble is a bit less lively and the signature a touch warmer. For headphones like my HD700s this can be a welcome change but for others the drop back in treble is a bit too steep and vocals take a step back as a result. Attack is sharper in ASRC mode as well with Sync being slightly more blunted but again a bit more note weight and a bit more musical compared to a more clinical presentation of the ASRC. One other note was most obvious when using the HD800 and less obvious with others and that is the ASRC mode does a better job of creating the stage than the Sync mode with sync losing a bit of the stage depth the HD800 is most famous for by comparison.

As you might guess, both modes have attributes that make them appealing but both have drawbacks as well. I really like what Sync does for the HD700 and HD800 tonality as it helps calm the extra treble energy both bring to the party. The bad news is you lose a bit of edge and stage in the process and it may not be a trade others are willing to make. Likewise, the ASRC mode is fairly typical of ESS signature and will be seen as a bit too cool, clinical and sharp-edged for some, but brings with it speed of attack and the larger stage we have come to expect.
One other thing to note, both mode and filter traits are audible regardless of whether the Aquila is used as a DAC, pre-amp, or head-amp so all filtering is done well before the output stage.


Pairings:

The Aq2 has a good bit of power on single ended and even more available in balanced mode so can handle a fairly wide range of the headphones and in-ears. Starting first with what it does not do well, super sensitive in-ears will have some notable hiss. I tried to use the Magaosi K5 in balanced mode and the hiss was pronounced. It was less so using the 6.3mm jack but still not dead quiet. For most in-ears that are not considered hyper-sensitive, the singled ended output worked well but balanced at times still has a bit too high a noise floor to be absolutely quiet. On the flip side of the spectrum, the single ended output lacks the grunt to really drive things like the He6 well as you run out of usable volume range a bit early. When run in balanced mode these fare better but still show the limits of the output power of the Aq2.

The Aq2 is much more comfortable with middle of the pack gear rather than either extreme and had no problem with several dynamics ranging from 150 to 600Ω and sensitivities from the high 80s up through 102 dB/mW. I paired it with the HD6xx, HD700 and 800 from the Sennheiser line and it worked well with all of them as well as with the AKG 552 and Beyer DT990 (600Ω) and 1990 pro (250Ω). Moving to planars, the Aq2 paired well with the LCD-2, the He560 and Sundara, the Verum-1, and Fostex T50rp. (The T50 did better on balanced output as it was somewhat volume limited on single ended).


Comparisons:

YULONG DA10 – most will want to know what is similar and what you give up when you step down from $1200 to $700 in the YULONG line-up. The answer is a class A/B amp section instead of a true class A found in the Da10. That difference in amps gives the Da10 a 2V output at 32Ω compared to 1.6V for the Aq2 and that gap stays at least equally wide all the way through the impedance range so realistically, the Aq2 gives up a bit of output power and a bit in noise floor in exchange for the drop in price. Neither supports MQA so no loss of feature from one to the other and both feature very similar construction.

Topping DX7 Pro – The Dx7 Pro offers a very similar feature set to the Aq2 with both sporting the same dac, same usb controller, similar power 1.6V vs 1.7V (single ended) , similar PCM and DSD support (although the coax and optical are limited to 24/192 on the DX7 Pro). The Dx7 pro is a smaller and lighter unit by comparison at roughly 1/2 the height and weight of the Aq2. Differences include bluetooth input on the Dx7 Pro and a remote control and while I am not in love with Topping’s universal remote, it is a nice convenience feature. These two go toe to toe with the Aq2 winning points for more and better tuning options while the Dx7 Pro wins points for bluetooth and I2S inputs, and a remote.

XDuoo Ta-30 – At first glance, this compare looks to have little in common other than both being Dac/amps and both being made with anodized aluminum shells. The Ta-30 uses the 9038 mobile version rather than the pro so is a slight step down compared to the Aquila, but both use FPGA chips to support the dac and both expose the filters to the end user to allow for tuning of the sound. The Ta-30 also brings bluetooth input to the game and like the Aq2 also lacks I2S input. Optical and coaxial inputs are limited to 24/192 on the Ta-30, and it does not have balanced output among its options. What it does have is 3Watts of output power compared to 1.6 for the Aquila so it can power some heavy hitters like the He6 that the Aquila struggles with, but it also has a noise floor a bit higher so sensitive in-ears may be a better match for the Aq2. Also worth noting, the Ta-30 does allow bypass of the internal DAC to use with an RCA analog input if you wish to compare DACs (I did using the RCA out on the Aquila into the Ta-30).

Ifi Neo iDSD – I feel obligated to mention this one as it has a similar price point and feature set with the idsd skipping the XLR output in favor of only a 4.4mm balanced port, but adding MQA support and bluetooth input to the mix. I am hoping to have a tour sample of it soon and will update this review after spending some time with the Neo.


Thoughts / Conclusion:

With the Da10 receiving a lot of good press and being well liked and the Aq2 being billed as the little brother to the Da10, I expected good things. The Aq2 largely delivers on its promise of being a scaled back Da10 with most of the advanced technology of the Da10 being brought down to nearly 1/2 the price of the original. It doesn’t lose much in output power either comparatively so those that like the Da10 but can’t justify the spend have another option. I really like the fact that the filters and modes yield very audible differences as far too often you have to really search for differences in signature and often they are small enough that only the most analytical of listeners will ever notice. The Aq2 does a good job of offering the user the choice of the standard ESS signature with its slightly cold, bright analytical nature or warming it up a bit and smoothing a few rough edges with the FGPA tuned version. Controls are simple to operate without a lot of learning curve or multi-layer menus to wade through. It would be nice to have a remote if using the Aq2 as a pre-amp but as a desktop dac/headphone amp it isn’t really needed. The places the Aq2 takes a hit compared to some of its competitors are the aforementioned remote, the lack of bluetooth input, and a slightly high noise floor for pairing with sensitive iems. None of those are deal breakers for me and the Aq2 did an admirable job in the DAC role of my 2 channel setup and in ASRC mode sounds a lot like my Bel Canto at a considerably lower price point. The Aq2 sits at a tough spot in the market with nearly every budget maker reaching into the $500-700 range and nearly as many high-end makers releasing entry level products in the same space. It does manage to carve out a niche with its tuning features and good looks and those looking at this price point would do well to try out the Aquila II as it does a lot very well.
L
Lu Mazzmarill
Great review! Did you pair it with closed back headphones like the Denon 7200 or the Focal Elegia?
Wiljen
Wiljen
I did pair it with a couple, Fostex 610, Campfire Cascade, and a borrowed DC Aeon Flow C. it did well with all of them but was particularly good with the Aeon in Sync Mode, and better with the Cascade (cloth pads) in ASRC.
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