Thanks David and Geoff.I've been having a problem which isn't directly to do with audio—it's to do with the Ubuntu realtime kernel—but I haven't got any answers from the Ubuntu forums and this is a real showstopper as far as doing audio work goes.I've tried the ubuntu realtime kernel several times. I'm not suprised by your findings. Check out these links. I would suggest you file a bug report to ubuntu launchpad.
Unfortunately, because I do actually need to work with audio in real time, I do need -rt. I shall certainly file a bug report, but I notice that the existing bug reports have been assigned low priority. Since it doesn't look like these problems are likely to be fixed anytime soon, I'm getting to the point where I have to consider ditching Linux and using Windows for everything. I need to be able to do a bit of audio work here and there and then get back onto other things, so rebooting all the time is not an option. The only other option would be to consider switching to a more audio-oriented distribution, by which I mean one that will also let me do normal desktop stuff (Gnome, Skype, Amarok, aMule etc. etc.) without too much hassle – I don't have the time to do the Gentoo thing over again. Would something like Fedora/Planet CCRMA fit the bill? I notice however that on the main Planet CCRMA page it says that not all packages have been compiled in 64 bit versions. Does that mean I should forget the idea?Do you really need -rt for your work?