Finally the Soekris DAC has been mentioned. But it cannot be compared to all the rest because the owner can set/chose/compare its digital filters. This adjustment can change SQ far beyond any cable, speakers, amps, DAC changes and its still very subtle. It's kind of comparable to the filters which can be set in HQPlayer (with upsampling) but that would need a relatively powerful PC at the beginning of the chain.
Over the years CD players and DACs have offered these kind of different selectable filters but the SQ improvement was rather questionable IMO.
There must be almost hundred different filters, in the meantime written by DIY audio members which can be downloaded from DIYaudio. The DAC itself comes with 4 different filters.
For people who really want to tweak their DAC with some understanding of the details of what they are doing there is also a long thread which explains how to do it. So IMO this DAC has an incredible potential which no other DAC can offer.