Xaborus, to do this topic justice would require countless pages of circular arguments, ending in frustrating stalemate.
So I'll speak on behalf of at least some subjectivists and get to the bottom line:
We don't care!
We don't care if the sceptics believe us or not. We're not out to convert anyone. If you can't, or won't, tell the difference between DACs then good for you - you've saved yourself a shed full of money.
We're happy to discuss our hobby with like-minded enthusiasts. We're not bothered if a different group of people disagree with us.
What we are bothered about is if some rude troll butts into our conversation to declare what gullible fools we are. We've already got that bit and are happy to continue regardless.
If you do want to follow the for and against arguments, then go to the Sound Science forum and try any thread about cables - there's more of these threads around and the principles are the same, just more extreme views.
Or the thread about high end audio being a scam.
A lot of the sceptics' points are worthy of note, but... I don't care :o)