My pro speakers sound great on my 17" iMac, on par with my $500 Sony mini system. Volume 1/2 way is plenty loud with iTunes. As for the bass, that's something I wondered myself. There is TONS of bass, and I don't see how it can all come from such tiny speakers. I read somewhere that the iMac base acts as a Sub for the speakers, which would make sense because it does have a speaker, and has weight so as not to vibrate. Any truth to that? It would explain why your G4 box doesn't have the bass!