[Guderbass]

Thanks Joel - look forward to hearing from you.

It's very frustrating, as my audio is now effectively bricked, as now not only can I not use ProTools or Garageband, I can't even play my iTunes library through the device.

As an avid (pardon the pun!) user of Macs for over 15 years, the major attraction has been their plug 'n' play compatibility with external devices. Avid/M-Audio has seriously dropped the ball with this one.

I know some users have suggested downgrading to an earlier Apple OS, but I'm reluctant to do so because...

1. If the system becomes unstable, Apple does not support it. Apple does not support downgrades.
2. Apple cannot guarantee the functionality of a downgrade. Mavericks changes the build on your computer.

Look forward to some sensible news on this issue!