I have a 7700 and it's dead silent! In fact that is one of the reasons I went with Outlaw, no fan. I did have a bad ground-loop hum problem that was caused by my overhead lights but that problem disapeared when I moved it to another circut.

That is really strange, the 7700 is a quality amp and it should not be doing that. I am curious to see what those dedicated lines do, I have been thinking about doing that myself, would be great to have regardless.