I've been losing my mind trying to troubleshoot this. Maybe one of you geniuses can help. I'm using an E-MU 0202 USB-2 interface on my computer (PowerMac G4, OSX 10.4.11). I'm using it more for music playback than for recording. I get noise that ranges from the ocasional buzz and zap to loud backround crackle. Sometimes it even degenerates to total distortion, which repairs itself if I turn the device off and on. Here's some troubleshooting I've done: 1) replaced the E-MU device. The store that sold it to me assumed it was defective and sent a new one. No change. 2) replaced the USB-2 card. Things got worse! 3) replaced the USB-2 cable. No change. 4) tried different outputs on the device (line out to stereo, line out to powered speakers, headphone out). No change. 5) compared to the Mac's built-in audio. This is almost perfect, although once in a great while I hear a buzz or zap. Of course, sound quality is low. Any thoughts? This audio interface draws its power from the USB port. There's no option for a separate power supply. I'm wondering if dirty power from the computer's power supply might have something to do with it. If this sounds likely I may try a powered USB hub. Thanks for any brainstorming.