So I recently bought a Mackie Onyx 400f from Musician's Friend. It was a factory reconditioned one, but it was only $399. UPS drops it off yesterday, and I hook it up after work. Plug my guitar in, and listen through the headphones and it sounds perfect through the internal mixer. Install their Tracktion 3 software, set it up to record, and start playing. It sounds aweful, full of pops, clicks and drop-offs. I thought I had gotten a bum device and I've read that certain firewire chipsets can cause issues (I'm using the one on my Intel motherboard). I fiddle with it for 2 hours, changing sample rate, sample sizes, everything and nothing fixes the problem. Finally I tried hooking it up to a copy of Abletron that I had installed. Recorded perfectly. Not being one to let sleeping dogs lie, I decided to figure out why Tracktion couldn't do the same thing. Just for giggles I hooked up my USB PodStudio GX and tried to record with Tracktion. Same pops and clicks as with the firewire 400f. At this point I've eliminated the 400f, firewire, and interface as being the problem. Finally, I change the "Number of CPUs to use" setting in Tracktion to 1 (instead of 4, since I have a quad core). Wouldn't you know it, it recorded fine with the GX. I tried 2, 3, and 4 CPUs, and got clicks on anything above 2. I'm guessing they never tested it on machines with > 2 cores.