Closer Examination

The xDuoo TA-22 is a desktop class DAC/headphone amplifier all-in-one device, akin to some others we have seen before. It comes in a single color option of rich blue, with a lustrous finish given to the thick CNC-machined aluminium chassis. The form factor employs a rectangular base that then gets taller with full assembly, although this current state of the product as you see above is a dense unit at just under 3 kg while measuring 26 x 19 x 7 cm. Given the lack of a remote control, it's best to keep the product within arms reach, at least initially, and you can also admire the design now complete with the large glass panel up front with the xDuoo logo and TA-22 on the left. Past the screen are the various headphone outputs in the form of a single-ended 6.35 mm (1/4") connection, a 4.4 mm TRRS balanced connection, and a full-size XLR output. I appreciate the inserts around the headphone outputs as well as the volume wheel itself, which is red in color, that helps break the monotony elsewhere, although the red was probably a bit much. The volume wheel is tied to a rotating encoder without any stops either direction so you can freely rotate it. There's also no marking on the wheel so you are effectively tied to the screen to do anything with the wheel—especially when the onboard menu is also controlled with the same wheel.


There's not much going on at the top, except of course for the cutout towards the left where you install the provided tubes. There are holes cut in the chassis for ventilation given this area would otherwise run warm, and we also see an X shape around the tube connections where the aluminium frames would slot into to act as pseudo-tube cages. There was an opportunity to make this more like the xDuoo logo but I am glad the company decided otherwise.


More ventilation is seen on the sides where we also find out this is a two piece chassis design in a blue and black color scheme. This is all the more evident on the back with the use of socket and Phillips head screws keeping the TA-22 together and promising an easier disassembly than most other products. Things get busy here with the various input and output connections which come clearly marked. There are two separate outputs depending on whether you simply want to use the TA-22 as a DAC or have the tube in the line-out as a dedicated preamp to control, say, active speakers. Likewise, you can use the TA-22 purely as a tube amp and have another DAC or analog source supply the signal via single-ended RCA or balanced XLR/4.4 mm inputs. Most customers interested in the product would no doubt plan to use it as a DAC/amp and thus the next section is all the more relevant given the plethora of digital inputs including optical, coax, USB (Type-B as expected), and there's also Bluetooth on top. Rounding off this section is the power delivery itself wherein xDuoo is kind enough to throw in a 110/220 V switcher if you plan to travel, as well as the expected 3-prong power cable input along with an integrated fuse. The on/off switch is placed at the top for easier access from the front and I am left impressed with the I/O options and layout here.


On the back we see more socket head screws as well as four raised rubber feet that lift the TA-22 off your desk to both provide additional grip and prevent scratches to the under body. These are held in place with Phillips head screws and are thus easily replaceable should you wish to install the TA-22 in a custom audio rack. Notice also the serial number stealthily etched here! At this point I decided to install the tubes and the tube guards by using a set of gloves to ensure no finger oils get on the tube body itself. Carefully align the pins with the socket and gently wiggle them in place—less is more in both force and vertical/horizontal movement—until they press down and remain in place. There remains some wiggle room for adjustment should you find the tubes not centered properly, but be aware that it doesn't really matter if they are tilted slightly. The aluminium tube guards just slot in place at the top as seen above and are mostly there as a deterrent to stop your hands, or that of others around you, from accidentally touching the hot tubes when the unit is running.


Given all the screws used and how my weakness is trying to take things apart to see how they work, I decided to disassemble the xDuoo TA-22 after all testing was finished. Keep in mind that I heavily discourage doing so for anything with a bunch of capacitors inside, and there isn't anything to gain here either aside from lost warranty. I wanted to disassemble the unit purely out of academic interest and it's a fairly involved process involving the volume wheel, various screws on the back and under side, a ribbon cable connecting the display to the primary PCB, and realizing how the chassis sections slide and align in place. This helps separate the blue-colored chassis that has the display still tied to it.


The xDuoo TA-22 uses a stacked PCB approach for its primary hardware, including an R-core transformer that isn't typically seen in such smaller units. Depending on where you stand on the whole audio transformer topology argument this would be a good thing or simply irrelevant, and I'll just mention that it does its job well enough in providing clean power as needed. There are various "audiophile-grade" capacitors in use here, including some Nichicon and ELNA caps from Japan in addition to xDuoo-branded units and some metal polyester film capacitors too. I haven't really been convinced as to the effect of capacitors on the sound signature but xDuoo talks a bit about it on the product page if you were interested. I'll talk more about the hybrid amplifier section on the next page, so let me instead wrap up by mentioning that the rest of the important hardware is on the main PCB below the daughter unit hosting the tubes. There are thermal pads and heatsinks employed here so it's not the easiest to identify, but xDuoo confirms the use of two ESS Sabre ES9038Q2M 32-bit stereo DACs—one per channel. There's also (based on my testing) an XMOS USB decoder as well as an AKM AK4118 optical/coax decoder to go with a Qualcomm QCC5125 Bluetooth SoC to handle the various digital inputs. All these provide decent numbers for a tube-based source, be it the THD+N of <0.02%, SNR of 125 dB, SNR of 113 dB, and crosstalk of >70 dB off the single-ended 6.35 mm output with the equivalent numbers being <1%, 118 dB, and >96 dB off the balanced outputs. It's not going to best the all solid-state implementations we've seen recently, but then again you shouldn't be looking at tube/hybrid amplifier sources for the best measurements anyway.