I needed a DAC for my multimedia computer and thought that a full pledged sound card (such as a Focusrite solo or 2i2) would be overkill for the job, as I only needed a stereo output.
First of all, the power supply is very poorly build, and as soon as it is plugged-in and supplies the DAC, a very distinct coil whine can be heard (hissing high-pitch buzz sound). This issue might be mitigated by the use of a better quality 9V power supply, though.
Then - and I do not know whether the issue is with the power supply or with the inner filtering on the DAC board - the power supply transient rejection is really poor: I have electric heating in my house and I could hear clicking sound whenever one of them turned on / off (same for cooking stove). (I must precise here that with another DAC the clicking sound cannot be heard, so it's not a power amplifier issue)
Finally, the Left / Right crosstalk (diaphony) is terrible!!! When setting the output to full Left (or full Right) in Reaper, I only get an attenuation of maybe -30 / -40dB on the other channel, so I cannot have the sound coming only from the Left or Right speaker, which results in a poor stereo image.
Overall I was really disappointed with this product and returned it right away. It's weird, as - overall - Thomann products are mostly OK (I mean, they're not marvellous, but do the job, not less, not more). I wouldn't advise anyone to buy this thing as it is now, and it would need solid improvements....
Note : contrary to what other comments mentioned, I had no issue with the optical connexion, and both the optical and coaxial link worked equally good (or rather bad, in my opinion).
