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,
A constant buzzing in the speakers is nearly always a "ground loop" problem.
The signal lines are carrying some sort of voltage differential. (almost always the power line freq or multiples of it.)
The solution is to isolate the offending item.
I just had to do my system as I bought new speakers (B&W 805s) and noticed a buzz that was unobtrusive in my former Maggie IIb.
I started by disconnecting the interconnects from th pre to the amp.
With the amp turned on the speakers had zero buzz.
So I then knew it was not the amp.
Then I reconnected the pre to the amp and disconnected most of the sources.
Turned on, still no buzz.
After doing a few more checks I finally discovered the primary problem was the cable from the digital out to the DA converter WHEN IT WAS FROM THE SCD 333ES. (from the Sony SCD777ES the same interconnect to the same input on the DA converter did not cause a buzz.
I also lifted the ground on the preamp to reduce the buzz still further.. (I maked those cords with a disconnected ground so I will always know that they are disconnected.
Also I plan on making a short cheater extension cord with reversing AC polarity in it to test the SCD 333ES for the problem I mentioned.
(My thinking is the cord is reverse hardwwired into the SCD333ES)
Anyway, this is what you gotta do.
Good luck.
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