What does this tell me?

With all of those things disconnected, does the noise still happen only when inputs are selected which have interconnects plugged into them (the interconnects being unconnected at the other end, if I understood your post correctly)?

-- Al

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

I'm suspicious of the Squeezebox. Is it connected to a computer via ethernet or wirelessly? If via ethernet, try disconnecting the cable. If wirelessly, try removing power from whatever is wirelessly transmitting to it. And of course keep in mind that any of these devices can probably continue operating for some seconds after the power plug is pulled, running on capacitively stored energy.

Regards,
-- Al

And unplug the Squeezebox's wallwart power supply from the ac outlet, if what you did was to disconnect the Squeezebox's power by unplugging the wallwart from it instead.