I'm in need of a sanity check here. I've been having this audio crackle issue for a while and have so far failed to find a solution: http://cycling74.com/forums/topic/audio-interface-acting-strange/
Some symptoms led me to believe that my MOTU is failing so I bought me a RME UCX as replacement. It's got both USB and FW so I thought I'd have the USB as backup if it turns out to be a FW problem on my system (though I already had swapped the FW PCIe card for another one).
No luck. Same problem still there, on both FW and USB...
By coincidence I thought of the 1st instant I encountered the crackling issue. It was during a show where I was channeling audio from Ableton to Max via Soundflower. On a whim I uninstalled Soundflower from my system.
And what do you know...? I've been playing my Ableton test set for hours and the crackling isn't appearing. Previously the issue always surfaced within an hour of playing (no Max in the loop here, just Ableton).
Soundflower was not in use before, just installed. Could it still have been creating issues?