Thanks to organizations such as DNK-Amsterdam, Steim and Amsterdam Conservatorium the city holds quite a number of talented musicians and a special vibe.
There are weekly events and concerts worth seeing and hearing. Also art-school kids organize pleasantly less serious but no less fascinating concerts with the most peculiar myspace extravaganza out there (like my favourite Hallo Gallo and Club Suburbia).
And don't forget various art openings and house parties where music often plays the main role. I have lived in this city for 2 years and music is my favourite part of it.