I have a friend offering to sell me his SBA2 ZS for $15 (a fair price from what I can tell), and I'm in the process of building a new computer. Until recently, I know the answer would have been "It doesn't matter, your speakers will drown out the difference."
Problem is, I now have a pair of Polk RTi4's bi-amped by a Sony STR-DE185 (I admit, I should probably change the amp, but I really like the way this one sounds.) The main weakness in the system is a deep bass response, (gets muddy if you push it too hard, I need to find a crossover for the woofer to allow me to cut off the bass response closer to the 160Hz mark.) but that's why I have a AudioSource in-line independently-powered sub.
My question: has onboard audio evolved enough to compete with the SB A2ZS? I had one a few years ago, but on-board back then was for office use. Or does it depend on the MB? In that case, is there any that are definitively better than an A2, or is it an at-best equal-to scenario?
I would say yes. On-board has come a decent away, but it's not comparable to better sound cards at a somewhat higher price point. The Audigy 2 ($100?) has a decent DAC that is probably better than modern on-board audio. How much better, I'm not sure.