My 7700 has developed a loud buzz in my rear channels, no audio just a loud buzz when it starts. Every time I turn it on it buzzes, I'll turn off then on again and usually on the 3rd restart the buzz is gone. Then it could play all day without a problem or it can reoccur in an hour or two. The buzz continues with my Marantz 7703 is powered off, I removed the trigger wire and that had no effect. I've had this baby for ever.... bought it new, what to do??? Thanks your advice.