It has to be said that it goes both ways; I've played commercial games which were soundtracked with freely available music the authors probably got off a compilation somewhere. I bet the composers never got any royalties!
As for audio tracks, I think that if AMP isn't prepared to host the 'exotic' formats such as TFMX, RJP, etc. then it definitely shouldn't be hosting OGG files. Don't try and compete with UnExoticA; stick to what you're best at. Since there's no way AMP would host any CDDAs which were not from a game of some kind (otherwise, where would you stop?!), there'd be a 100% overlap between the two sites. Just stick to collecting tracker music from every source including, but not limited to, games, and AMP will still have a purpose.