I haven't tried disabling edge with bossprefs, but assuming it actually does disable it, then, yes, that will solve your problem. You will, of course, lose service when you lose 3G. No biggie if getting rid of the buzz is top priority.
Just so we're clear here, though, are you getting buzz when the phone is not plugged into anything and just near your equipment? Or are you plugging it into something (like your stereo via headphone jack or dock)?
If you are plugging it into something you can try using ferrite beads. These worked great in my car for this purpose.
Otherwise, if the phone just being near the equipment is the problem, then you have much less options besides turning off edge. You could try to determine exactly which piece of equipment is causing the problem and try to shield it or add ferrite beads to it's speaker wires (signal wires), but I suspect this option isn't really possible. I've heard that putting a bunch of tin foil around the phone's back helps also, but I've never tried this.
Anyway, good luck with whatever you try!