When you have the volume at 100% when using the software volume control, is that bit-perfect?
Tag
??
Its a way for me to subscribe to the topic because I am interested in the discussion.
Judging by how the program works for Windows, yes! They all have a volume control, and at the maximum it is considered bit-perfec. But I would not recommend to use software processing. 
Probably not! With volume control enabled, the bit stream has to go through several layers of software that are capable of modifying these bits otherwise it is not possible to adjust the volume. You have to rely on all those layers to keep all bits unaltered if they do not have to perform any filtering/adjusting.
I would suggest to turn volume control off, which than bypasses all these layers and no altering can be performed.
Why turn it on anyway if you don’t use it by leaving it at 100% 