I just want to re-iterate the points Jesse Graffam made across several posts:
1.) "On some audio cards, MME and DirectX is 1:1 bit accurate"
2.) "it also depends on if you're asking about lossless codecs, or lossy codecs"
(IOW, there are differences in output between decoders...)
3.) "Some of those APIs, on some soundcards, are not bit accurate to the DAC."
4.) "...there can be differences, that can sometimes be audible to some people on some systems, with how they sound when decoding lossy codecs. The reference spec for a proper mp3 decoder obviously isn't stringent enough, or I wouldn't be able to blind ABX several different reference decoders."
5.) player alteration of bits has been proven to Jesse's satisfaction in other threads however, "If it actually makes an audible difference... I'm definitely NOT going there.
Seems pretty informed and rational to me...
It's easy to pick apart someone's post without reading what they've written earlier in the thread.
I don't know about bit accuracy between soundcards and software (I've only overseen one driver project for a sound card manufacturer ages ago), but I can verify different decoders produce different results when dealing with lossy formats.
I just did some research into callback procedures for various audio specs and couldn't immediately see how the bit stream could get munged but I don't doubt it's possible, there are a lot of variables in play, especially on windows.
On Edit, Mac players aren't on topic but I guess the context might warrant mentioning:
Audiofile engineering's Fidelia and Sonic Studio Amarra (which I think is a workflow fail because it uses iTunes rather than running standalone).