I thought both have to be bitperfect than only you can do something with the timing, like making bits shorter in time when the angle of the sinus is steep and making the bits take more time on top of the sinus....
Haha, nice thinking. But no. As usual and always no DSP from my hands (but don't upsample of course).
The bright one probably is "wrong" (it is much more difficult to let the "easy" one be the wrong one). So, if the difference is so apparent, just think of a buggy interface (what did the Chinese try to copy this time ?
).
Btw, strange that the coax connection doesn't allow for 24/96 !?
Note that when you don't use the digital volume, the output to 16 bits and 24 (actually 32) is the same. This is not so when you use the digital volume, because then the 24 bit output is still the normal output (no losses) while the 16 bit output *does* have losses. At more attenuation this may create a more rough sound, but in the end it's pure distortion. I don't think I'd ever call that more bright, so I don't guess that is the "problem" (hence you won't be digitally attenuating).
Peter