I was almost convinced that the arguments about clean digital signal and clock drift were valid only for very end system and with well trained listernes. But i must admit that it improved even on a rudimentary system : a toppling Mx3 as DAC and amplifier (currently replacing my denon 1500 that m m trying to get repaired) and my Triangle Lyrr from around 2000. The gigh are sharped and more defined, for the bass i hear much more harmonic and details (that also exist without) just appear more obviously. Last the dynamic of the sound is much larger.
So of course for 20 euros it is a bargain.
Yet there are issues, 1) the first it that the device is delivered with spacers but those are not to be used since they prevent the Pi to fit in bargain box. So i lost quite some time before i became 100% that the problem were the spacer. Once i had removed them everythinh actually fitted almost perfectly. The second is that with the bargain boxing (the one that ost a few euros) it is impossible to plus the Toslink connector. I know that this connector is aymetric (i have been using those for 20 years) and i have 3 optical cable at home, all a bit different. None fits. If i remove the boxing i can plus a Toslink connector but i need to psuh super hard, and to unplug i need to pull so hard that i m afraid to break the Pi-card.
Note i bought this device to use it with the SPDIF connector so i don't mind to much, but honnestly it is improper.