Ah... One of my specialties.
Options:
- Streaming audio
- Embedded Flash
- Embedded Windows Media
- Embedded QuickTime
- Embedded Real Audio
Windows Audio (WMA9) is the BEST. Screw what other people say. it is the absolute best. QT is crap. Real is crap.
However... the best WEB audio is Flash for compatibility reasons.
See http://maven3d.com/en/experience_it.asp?PID=1 for an example of Flash and Windows Media. (I would never put up Real or QT.) Both versions are embedded in the page completely. MIDI is generally poor on the web. I would never use it. The Window Media uses WMA while the Flash uses MP3.
However... for serious high-end stuff, AAC or WMA9 Pro are the only two viable things out there at the moment. Proprietary stuff just won't cut it if people need to download stuff. And WMA and AAC are two of the best audio codecs available. Other good stuff is DTS, MLP, and AC3. But I'm quite sure that you can't afford them... I know I can't... They would all require some serious nasty programming to implement on the web.