H/W Buffer Causing Sync Errors

[appleaudiond]

I'm mixing and I'd like to increase the H/W buffer to increase processing power. But when I increase the buffer, my tracks go out of sync. For example, if I'm listening to drums and I solo the snare and overhead track at a buffer setting of 256 the tracks sound like they were recorded at the same time. When I set the buffer in excess of 2000 the tracks flam against one another.

Any help is much appreciated.

-Nate