[PD] [ot?] pd and ableton via jack

[Myo]

hello list,

I apologize if this is too off topic, but I figured there would be
many people in this same situation here that could help.

I'm trying to route audio from pd and ableton live via jack on mac os
x 10.3.9. pd is 0.38.4-extended, ableton is 5.2, and jack is 0.74.
interface is presonus firebox.

I get everything running ok, but still get pops and clicks. changing
the buffer size, number of physical i/o, number of virtual i/o,
closing background processes, all have no effect. both live and pd
function normally without jack, so I know it has something to do with
the interactions of the 3 programs.

any suggestions are very welcome.

thanks alot
cory