Not clear to me that markg has lifted the ground to see if it solves the hum problem, so all this speculation may be moot - at least in his case.

I have had the occassional hum problem that was not solved by lifting the ground, but most are. Particularly in complex, multi-component sytems ground-loop hums can be VERY difficult to erradicate. I had amps with a lifted ground for years without any problems, but then read about what could possibly happen and got all nervous about it.

My solution was to buy a few Ebtech Hum-X devices from amazon. Not cheap, but at $70, not too pricey either. Supposedly, the device isolates the ground but does not lift it, so you get the hum-elimination benefit without the shock potential - at least, that is what the device manufacturer claims. At the very least, every HT owner should have one sitting around as a diagnostic device because sooner or later we'll all get a hum problem (cripes, I sound like a shill for the product ....).

Last edited by Simon; 2009-10-26 05:04.
My Kit: 861v8+ID41, 800v4, UHD722, MD600, MS600, MS200, Oppo BDP-203, Genesis 201, Genesis 350 SE, Genesis S4-8 Sub, BG 520i, VTL MB450 II, Krell Showcase 7, Genesis 928 Subs, Danley DTS10 sub, SVS Ultra 16 subs.