What does this tell me?

It's a dedicated 20 amp circuit, with two outlets about 8 feet apart. It was
installed by my dad, who is an electrician.

One outlet has a TRL power strip plugged into it. Into the Power strip is the
Squeezebox, Oppo DVD player and Behringer DEQ. I have a Krell integrated
plugged straight into the wall.

The other outlet has Power Wedge power conditioner plugged into it. Into
that conditioner is a plasma tv, satellite receiver and sometimes a playstation.

I also have a Vandersteen sub plugged straight into the second outlet.

Besides the other good suggestions which have been offered, I'd suggest that you try unplugging the Power Wedge (and therefore everything that is plugged into it), and also try plugging both the Krell integrated and the Vandersteen sub into the TRL power strip (assuming it has sufficient current-handling capability).

Both the plasma tv and the satellite receiver could be generating rf interference that may be coupling into the low level components. The problem could also be worsened or caused by ground offsets (differences in potential) between the different outlets, or resulting from having some things on the conditioner and some things not on the conditioner.

Also, I'd suggest taking a portable am radio, tuning it to the bottom of the band (around 550kHz), and walking around with it in the area of the system to see if it picks up significant rf interference. As was mentioned, both dimmer switches and compact fluorescent lighting (or full-size fluorescents, for that matter) can be potent rfi generators, especially if the fluorescents are nearing the point of failure.

Hope that helps,
-- Al

Does your interconnects or speaker wire run across any power cords? This happened to me when I had the Odyssey Stratos amps in my system.

Get some two prong adapters to see if it's a ground loop, try amp and/or sub first.

I unplugged the sub, still noise. I unplugged the Power Wedge with the tv, &
satellite receiver, still noise. I took a radio tuned to about 550kHz and walk
around with it, whenever I got near the side of the rack with the amp, Oppo and
Squeezebox, it went nuts. I then unplugged the Squeezebox, still noise. I then
unplugged the Oppo, still noise. All that leaves is the power cable going into the
amp, the interconnects going into the amp, the speaker cables coming out of it
and the amp itself.

I guess I'll try re-routing cables and see if that makes a difference. And I'll try
Samhar's idea of the two prong adapter.

Thanks for all the input, keep it coming.