mixxx and jack, horrible sound playback

[Jason Schaefer]

 I built the latest svn of mixxx with the portaudio snapshot (for jack
support) and sound playback is horrible. It has a crunchy digital
delay sound. If I raise my frames/periods to 1024 (latency ~48ms) it
sounds clear. This is true for my built in intel AC97 and usb M-Audio
fastrack pro. Both of which, I used successfully in the past, using
this same hardware. I recently installed ubuntu studio (installed from
dvd). Do you think this is the issue? Has anyone experienced this on
ubuntu studio? I posted to both lists just in case...

Thanks
jason