@amirm, can you please also spot check preamp outputs? Output impedance would be interesting if this is something you can measure for line level outputs.
As for headphones, does the balanced output have the same performance when used with SE inputs?
Can be a hardware failure, try on another PC, if the same issue you'll need to try to get a warranty replacement from the place you bought it from or contact Topping support they may be able to fix it.
I thoght maybe I was missing something. I can appreciate the package but in my view all these streamers become obsolete sooner or later as the technology/protocols change after the maker stops development. Then the software is usually buggy to begin with and the bugs tend to never get resolved...