How to isolate culprit in buzzing speakers?

recently began auditioning a friend's PS Audio-600 power plant. was amazed by the overall sonic improvement to my rather modest system. despite the musical upgrade, i noticed a bizarre, audible, pulsing-buzz coming from inside my amp. after some trouble shooting with PS tech support we traced it back to surges in the PS-600 and sent the unit back to be serviced.

knowing what it could sound like with the PS - i had no desire to listen to my stuff while waiting on the repair. when it did return - i plugged all my gear back into the PS-600. fired everything up and now heard a rather loud buzzing coming this time from both speakers.

i'm troubled because my system does not sound nearly as good as i have heard it in the past {either with or without PS-600}. been considering upgrading my amp, wiring and perhaps speakers to gain more musicality. but, something tells me i should hold off until i get to the bottom of this annoying problem. what say you?

what steps can i take to isolate the culprit? could the 'surges' from the 600 have anything to do with my gear sounding off?

current system:

power plant: PS Audio PS-600
pre-amp: Audio Research LS3
cd: Naim CD5i
amp: Rotel RB 981 {120 wpc}
speakers: Paradigm Studio 100's V3.
speaker cables: Transparent "The Wave"
interconnects: Interlink "The Link" 200

thanks in advance,
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Try leaving your gear on for a few hours or over night before listening again. This might be your culprit.
get acheater plg ..they are gray and plug it to the cord going to the wall from your p 600 see if it goes ls3 has the ground loop so i lifted ground on can lift ground on the 600 by reading the manual
If you have your cable or satellite hooked up anywhere in this system disconnect it at the wall before it goes into the first device. The buzz will go away..Then call the provider to install a dc blocking filter.Tom