Well I am glad to see that I have company. I purchased the 990/770 a couple of weeks ago and Tuesday was the first that I had time to work on it.
Right off the bat let me take my hat off to Steve for giving me some ideas as to locating the HUMMMM and for being patient.
I disconnected the cable line and I still had the HUM. Then I checked all of the balanced cables one at a time. Still had the Hum. Then for the third time and I checked all connections to make sure that I did not miss anything. Still had the Hum. The final step as suggested by Steve was that I run an extention cord to an outlet that was not on line in my Home Theater.
Connect this line to the 7700. Turn it on and see what happens. BINGO!! No Hum.
My friend and I added up the wattage of all the equipment that I have even though we knew that I would never be using all of them at the same time or even to there max output. The formula is Amps=watts divided by Volts. The result was that with all the equipment that I have there was not enough amps to handle it and the result was the HUM.
I decided to run three more seperate lines into the room. I have two line conditions rated at 1800 watts max along with the 7700 at 1800 max. that is approx. 5400 watts right there. Not to mention the other equipment. I spoke to a certified electrician about the problem and he told me that if I wanted piece of mind to install the new outlets. Overkill? I do not know. What I do know is that I have no HUM.
Also if I decide to have any additions to the equipment I won't have to worry about the dreaded HUMMMM!!!
I do not know whether or not you guys are thinking about going threw the process of installing additional outlets on seperate lines but I thought you would like to know about a lasting cure.
Thanks for reading.