I voted both. Music is the most important, ofcourse, no doubt about it. I won't be listening to music I don't care about just because it sounds good.
but the music does get better when you've got some decent audio. music from my stereo's speakers is still music, and if they'd play some decent stuff on the radio I'd probably enjoy that too. but only for background sounds. not the sit down and close your eyes kinda listening. and listening to those stax's was just as exciting, even more actually, as buying a new cd.
and besides, it still is a hobby, nothing wrong with getting some good audio for the fun of upgrading. new-toy-hype is addictive
you need a fix every now and then