Hi,
I posted something similar before and got some good feedback.
I have an MBox plugged into my TiBook (867Mhz), and I have plugged the Edirol MA-20D near-field monitors into the MBox. They sound great, so I sometimes use them as my main speakers for everything, including listening to iTunes. Here is my problem; occasionally - and I don't know what triggers it - my monitors just go nutz! I get this really loud, destructive sounding static, and I can't seem to eliminate it without shutting down the computer and re-booting. I have the monitors plugged into the 1/4" stereo jack on the back of the MBox using a 1/4 stereo to RCA cable. The same problem happens when I record, making it almost impossible to record. The speakers are new, so I could return them if they are defective, but when they are hooked up to any other device (including my 'Book's headphone jack) they work perfectly. So I guess it has something to do w/the MBox. Any help would be truly appreciated.
JT

I had a similar problem using the Edirol MA-20D's with Reason 2.5. I'm using an Edirol UA-1X for the audio interface. The speakers started emitting lots of noise and crackles for some reason, but I found that going to Audio Midi Setup in the OS X Utilities folder, clicking the properties tab for USB audio CODEC, and setting format to 44100.0 Hz and 2ch-16bit seemed to resolve the problem. Needless to say, this was not mentioned in the shitty Edirol manual. Hope that helps.

hey man you just saved my life.
Just bought edirol ua-1x. Using mac os 10.3.4 . Did what you said. changed it from 8 bit to 16 bit on the audio output for the Core Audio and it worked. bye bye fuzz and crackle. THANKS