ground loop questions

positive to positive, negative to negative

Jaf2290 - Plugging components into a common receptacle is a good way to minimize the chance of a ground loop, what you are trying to avoid is a difference in impedance to ground between two components. This is also why a heavy gauge ground conductors are sometimes helpful (keeps everything at near zero impedance to ground & so minimizes differential). For what it is worth, some manufacturers reccomend plugging all components into a common power strip as a starting point.
Phase in household wiring is typically thought of in terms of which side of the incoming 220v supply you are tied to (the center is usually grounded so you end up with two 110v sides or phases) , positive and negative are usually thought of as refering to polarity.
Viiu - good luck, ground loops can be a nuisance. One thing to remember is that a ground loop can't come from one component. To have a gound loop you have to be tied to ground at two different places (i.e. there has to be a loop for current to flow through), so you should be able to break the loop (and eliminate the noise) by breaking the connection at more than one place.

A note that I am not sure applies here...I had a ground loop hum even when everything was plugged into known dedicated outlets with a known grounding point.

My problem ended up being the cable connection to my HD cable box. Grounding the cable where in comes into the house, to the same place all my A/V gear is grounded solved the problem.

I never would have thought the stupid cable was the problem!

Dbld, its usually the simple things that "get us". I am running only a 2 channel system with no tv in the room at all.. i think its something i will have to live with...i dont feel like tearing apart my gear/home to find something that may or may not cure what i have...granted, if it was an easy fix id do it, but as i cant hear it from listening position, not the end of the world

But I know...just knowing it's there would bug the heck out me.