sonyrules said:
There is a slight difference, Its all in the high end, symbols and stuff like that. But it still sounds alot better than MP3 and WMA
I certainly can tell the difference between 192kbps AAC and the CD, which is why I still buy CDs, and use my iPod as the modern day equivalent of a cassette tape player. Nobody expected cassettes to sound as good as the vinyl (and, especially later, the CD) and I don't expect AAC to sound as good either, but it makes the music a lot more portable than CDs, and that's definitely worth something. And, it sounds a lot better than FM radio. Regarding WMA (and I'm talking version 9 here, not the older versions), I think it does a pretty good job, and in my own listening tests, I've been able to hear certain things in a 192kbps WMA track that I couldn't hear in a 192kbps AAC track. However, with that said, I prefer AAC over WMA, just because to my ears it sounds a bit warmer. WMA tends to be too bright for my tastes and I found that if I listen to WMA tracks long enough with headphones, I'm left with this feeling that my ears are over-stimulated (I don't know how else to describe it -- but it almost feels like my ears are tired).
Regarding buying compressed songs (AAC/WMA/MP3) through an online music store, I'm not sure why anyone would want to do that, other than the convenience of getting the music faster, and using it on a portable (if that's all you wanted to use it for). I'm old enough to remember when record labels first started releasing albums on cassette tape. Then too, I wondered why anyone would pay the same price for a cassette as they would for the vinyl. And some of those first cassette releases sounded horrible (The Rolling Stones' "Some Girls" cassette comes to mind). But ultimately, I realized that people weren't paying for the quality. They were paying for the convenience of not having to buy the album, and a blank cassette, and then record the album to tape -- especially if they mostly listened to music through their car's tape deck, for example.
Anyway, this is a long-winded way of saying that you shouldn't consider AAC (or any of the other lossy formats) as a replacement for the CD. They just enable more/better ways of listening to music.