Okay, went out and got three of the "3 prong to 2 prong" adapters. I disconnected everything except the XLR cables from the preamp to the amp and all speakers;

* Just the amp on, dead quiet! smile

* Took the 3 prong Plasma electrical cord and used a 2 prong adapter and plugged it in and I got buzz

* Used a 3 prong adapter on the Outlaw 7700 amp with the TV using the 3 prong cord and I got buzz

* Used a 3 prong adapter on the amp AND on the plasma and the buzz is 90% GONE! smile


I tried connecting the TV to both the dedicated outlet and also to the Monster Power bar and that did not make a difference.

For experimental value, I connected a ethernet cable and downloaded and installed the updated frimware. While the process was running, there was no buzz, but when it restarted, the buzz was there.

Thoughts?
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Panasonic TC-P65S1 65" Plasma HDTV, Marantz AV 8801 Preamp, Outlaw 7700 Amp, Klipsch RF7 (X-over dean G modded) RC7 (X-over Dean G modded) RS7 CDT-5800C speakers, Outlaw LFM1 EX Subwoofer, Oppo BDP-93, B & O Turntable, Toshiba HD-A2, Sony CD & DVD 400 disc jukeboxes, DirecTV HD-DVR, PS2, PS3, Wii, Harmony one remote, Monster PowerBar 1200 for the TV, sub, PS3, HD DVD and Wii, Tripp Lite Isolation Bar for the Amp, Pre-Amp and other sources.