Thanks, that was very informative... it all seems to be *almost* related, but not quite. A lot of the "multiple sound card problem" description seemed familiar, but my system is 32 bit, so I'm not sure how applicable that is. I have installed Alsa 1.0.16 and fixed some mistakes i made prioritizing the IRQ thread. It seems much better (the biggest difference came when correctly getting the interrupt for my card set to real time), but i still get about 5 xruns per minute at 1024 frames. cat /proc/interrupts tells me there are a couple of other devices on the same interrupt with my card... three in fact, two USB controllers and one ethernet controller... will that matter? any way to change it if so? I'm starting to think I might be out of luck... Thanks again for the help though, this has all been very educational.