Thanks, guys. I redid the ferrite core around the end of the power cord, but it didn't change anything. I disconnected all other cables...no difference.
I was going to lower my house about 4000 feet and then realized that I didn't have to. Phew.
I still need to put something between it and the back wall - not too difficult, but the thing that I have in mind is covered in Niki's hair...so it'll take time to clean it off. Well, them off...I plan to use two identical foam dog beds that should help absorb some sound. Just a test because Niki uses them.