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).
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.
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.
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.
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.
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).
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.
- Sound Quality - 8.5/108.5/10
- Connectivity Options - 7/107/10
- Output Power - 7.5/107.5/10
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.