Aha thanks for getting me up to speed, this issue goes back some time I see.
Could the future new mainline kernel solve this issue?
I read some more on pro and consumer audio the last hour and I now wonder, does the distortion at +24dB occur at the output of the DAC or does it happen within the amplifier. It occurred to me that it might be possible that if you connect the dac to professional gear there will be no distortion. If that would be the case, it might be possible to buy some converter from pro audio to consumer audio and set the dac to +24dB.
Just now, in the new/latest release I set alsamixer to 100% and it says 0dB. Not sure what alsamixer said in the previous release. With worse I mean, it now looks like it’s good (in alsamixer, my first thought was it was fixed, only read your post after that) but nothing changed. Output did not become worse (or better, just the same).
Seems there are converters (for pro to consumer and vice versa) but I cannot find RCA to RCA. It seems the +24dB (or +4dBU) is connected to a XLR connector and +0dB (-10dBU) is connected to RCA. So you would have buy a RCA to XLR connector converter and then this audio convertor:
amazon.com/Rolls-MB15b-MB15 … B0002IL4B4
Or hardkernel just could limit RCA outputs to 0dB which is standard?