Originally Posted by: renPRS has covered it, but I can vouch for the cables. I had some random cheap ass no-name patch cables... and I had a bit of noise which I needed to gate. I switched them all for Van Damme cables a while back, and now I can only get any noise at all by using my CS3 compressor, which I guess must just be a bit crappy....

expensive, but worth it (for me anyway!)...

yeah, i can vouch for cables too. I used to install high end stereo systems and switched to Monster Cable years ago when I heard what they can do. Definitely expensive ($250 for a pair of 3ft directional RCA cables to connect my CD Player to the stereo system) but worth every penny as long as there's no weak point anywhere else in the system.

I've got the same hum problem myself whenever I use Boss Multi-effects units. Especially near the computer monitor.
The only way around it is to bypass the pedal altogether, record direct line-in and then apply effects later using VST plug-ins.