I have had this M-Audio Firewire solo for quite a while and it has worked great - until recently.
I
think my problem started happening after I updated to 10.4.9.
My problem: Audio that comes from my browser app (YouTube) does not play through the M-Audio. Instead it plays through my desktop's internal speaker.
It works fine in every other situation. Final Cut, iTunes, Quicktime, DVD Player - they all play the audio through my external speakers. Browsers don't, though! Both Firefox and Safari do this! (or don't do it

)
I'm guessing I may need a new driver, but at the time of this post I have the most recent driver.
The only recent significant change is updating to 10.4.9.
I am looking for another individual on the interwebs who has experienced the same thing. Now it's time to call M-Audio and let them know about this issue.