As I told you I feed AES/SPDIF inputs of RME and made records of bittest files via USB.
ADI's display always shows bittest is passed. When i play all these records ADI's shows the same - bittest is passed.
Believe me or not, but HEX-editor is not a kind of "magic tools". This is a most transparent (and primary) way to see what's is changing on audio data, no jokes. You just looking on table of binare codes. Its simple. Then i put original and recorded audio to the HEX-editor and apply offset because length of files not equal.
I have no issues with 24bit audio, recorded from output of SOtM tX-USB. I have no issues with 16bit audio, recorded from optical output of Airport Express. After offset apply tables of bits stays the same, no difference from originals. Except one case!
I have difference between original and recorded files only when i use SOtM tX-USB as source for playback 16 bit audio. It was recorded as 16 bit already. When you look on HEX-tables of recorded files you can easy find аdditional zero words between original bits. So tables of bits was changed actually. Anyway, even whan i play recorded files, ADI will show - 16bit test is passed however. Thats I just want to note.