As a cross-platform Windows and Mac user (I really have to be as a
writer), I can tell you I really miss Mac OS X's brilliant Core Audio
when I'm on Windows. And looking at Apple's updated Core Audio page for Mac OS X Tiger, Core Audio is only getting better:

  • Core Audio file format allows 64-bit files (bigger than 4GB), supporting any QuickTime 7 encoding (uncompressed PCM, MP3, AAC, whatever you want)
  • MIDI/Audio Device Aggregation takes the easy
    multi-interface support in X and ratchets it up a notch, with the
    ability to use multiple devices as though they're one device, assign
    different channels to different apps, etc. This should make MIDI and audio routing easier than ever.

(read more for upgrade advice)

There's nothing earth-shaking here for audio. (If you squint at the
screenshot, Audio MIDI Setup looks like it's been tweaked!) But if
you've been waiting to upgrade from an older OS X, do it already! While you're smart to wait a few weeks to figure out initial compatibility issues (like making sure copy protection works), this summer
could be a great time to get the latest version of X. I keep running
into Mac users who complain about compatibility issues, performance,
and other MIDI and audio gripes, and then find out they're using
10.1.x, when 10.2 and 10.3 each offered major improvements for Mac musicians.

It's not simply a matter of having the "latest and greatest" — it's a
matter of having the easiest, most reliable OS for music-making so you
can make music instead of stressing about your system. There are bumps
in any OS upgrade, but Apple has done a great job of keeping its music
market in mind, and not just for apps that say 'Apple' in the about
box. So get ready for a rainy day in June to put a Tiger in your tank.