When running Logic the sound will suddenly stop for several seconds, then come in again, as though catching up a bit.
I also notice this with iTunes.

This doesn't happen when audio out via USB.

any ideas?

pete

Intel Mac Pro5.1; 2.4 GHz 8-Core; 14 GB RAM; OSX 10.6.8; Logic Pro 9.1.6;
RME Fireface 3.06; Sonalksis; Synthogy; NI; Arturia; Korg;
Omnisphere; Trillian; Toontracks; Celemony; Flux; Airwindows