The question is, why are you listening to MP3's in the first place? FLAC or GTFO.
Meh, all of my music is mp3. I've heard FLAC files, and they do sound better, but it's not really worth it for the file size. Not to mention my Zune doesn't support FLAC files. I get no more enjoyment out of FLAC files than I do out of high quality MP3 files (320kbps) The difference is there, but I'm not going to waste a ton of space for a small quality increase. It's also all about convenience. My Zune doesn't support FLAC files, and even if it did, it wouldn't have enough room to hold my entire music collection. That is a big problem. And even if it did, I'm not willing to spend hundreds on headphones just to hear the quality increase FLAC brings. It doesn't make sense.
As for speakers, I don't know much about them. The only speakers I have is a Kicker ZK350 Zune dock and 4 new speakers I just bought for my car. 2 rear Rockford 6x9 speakers and 2 front Kenwood 6.5 speakers(old ones sounded like shit). No need for a subwoofer as I don't listen to anything that is supposed to be bass heavy. My speakers provide way more than enough bass. You can talk about how they aren't the best quality all you want, but they sound great to me and I didn't spend all that much money. I think the same thing applies to these computer sound cards. Sure they may not be the best like some claim, but I'm willing to bet they cost much less than the super high end amps and what not. It's all about value for your money.