I once had a friend (he still is actually) who kept insistnig what WAV sound better than FLAC. No matter how much I tried to explain it to him, WAV was better. According to him, FLAC was compressed, thus less quality.
I say it again - your soundcard has 0 effect on mixdown quality when making an export/mixdown/bounce offline
Don't believe it? Turn off your onboard ac97 and unplug your fw - it will still mixdown, even though there is no sound card present on the system. It's all math done by the CPU.
Of course a better soundcard will help you mix better - but we were not talking about it.
Colin - you mean if I have a poco or uad or something I must make it online? Offline will not work?
when using my own mastering - dither it and export as 16/44.1, when someone else is mastering - 24/44.1 (or 32, depends what they want).
no point in using anything over 44.1. too long to explain why, just take my word for it