I listened to my 990/7700 successfully all day. Tonight I attempted to plug in my new surround speakers to my 7700 and no sound comes out at all. I'm stumped. I turned off the 990 and the 7700 at the rear and plugged in the banana plugs at the rear of the 7700 for sr and sl. The r and l were already plugged in and worked fine. Now, nothing works. The only thing that has some sound is the sub, which is plugged into the 990. The red light on the 7700 usually turns blue and now it simply remains red. I tried turning it off and on 5 times, but nothing changes. When I push the power button on the front, the switch doesn't engage. Please help.