I've been aware of xDuoo products for a while now but mostly from the side seeing as how the company has a vast portfolio of headphone amplifiers that seem to offer tube output stages (or lack thereof) at extremely low prices. My immediate mindset would have been "surely that could not be any good?" as recent as a few months ago where I was still a proponent of solid state everything. Indeed, I still maintain that solid state sources have benefits that tube amps simply can't get to anytime soon, be it with the less amount of fiddling needed, no worrying about tubes needing replacement over time, and of course the part where tubes are hot and can hurt someone if they are not careful. Then there's the part where $100 can get you a DAC/amp with decent and clean power that may out-perform the more expensive tube amp in detail retrieval, as well as having the leeway to work with low impedance IEMs just as well as more demanding headphones.

The xDuoo TA-22 is a hybrid tube amplifier, as opposed to OCL/OTL tube amps, in that it uses two 12AU7 tubes as part of a dedicated preamp stage whereas the actual outputs are driven directly off solid state transistors. This means it does end up more flexible in what it can drive, and certainly has a lot of power to supply as needed. It also measures better than a lot of purely tube output amplifiers and has the benefit of having a DAC section to be a dedicated desktop all-in-one unit. I will also give xDuoo props for a rich selection of inputs and outputs which are laid out quite well, and you can use the TA-22 purely as a DAC, a preamp, a headphone amplifier, or the whole shebang simultaneously. Wired connectivity over USB and wireless over Bluetooth in addition to analog out to active speakers ended up being my combination of choice, with some dynamic driver headphones faring better than I expected going in. You do get some of that tube warmth and emphasis to lower order harmonics, especially with guitar strings now having that extra twang that makes you go yeahhhhhhh in your head. Then you compare it to a less expensive solid state source and almost immediately note how it isn't as detailed.

For what it's worth, I still maintain that a hybrid tube amplifier works very well. Indeed, the expensive Headamp BHSE is my preferred e-stat amplifier and it's not very tube-like either. Then there's the $15k HIFIMAN EF1000 that ends up with a more pronounced tube preamp stage and is one of the best headphone and speaker amplifiers on the planet. The principle is fine thus, and it comes to the execution of things, whereby xDuoo ended up going with a middle-of-the-road approach that I am not sure works well enough. It gives you a taste of what tubes can do,especially considering the other two mentioned here cost far more, but leaves you hanging just as it gets started. Perhaps there are other amplifiers in the xDuoo lineup that you can approach next if you so desire, or even attempt tube rolling if the TA-22 ends up responsive to it, but at this point I feel the TA-22 is a fairly niche solution that works well for a few popular headphones and locks you to them.