Sounds like a circuit overload. Try plugging the amp into a different receptacle on a different breaker. There should be no way for the amp to sense the status of the 976 without the trigger connected. Amps can have large inrush currents when first started. If the current is still there when the 976 comes on the amp may go into protection mode. Check all your connections to make sure no stray wires are crossing. As a extra check look at your trigger settings in the menu.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner