Speaker Hum

play some tunes, and unplug the HDMI cable to your tv from cable box.

this was my problem. when critical jamming, i unplug the HDMI cable. as quiet as a nun double clicking the mouse checking email.

 also I bought some Belden better shielded cable for amp to preamp, worked also !

Belden cables shielded better than the qudioquest topaz cables, have another pair, forget the name, great stuff, but the bolden shielded the radio tower, as i had high pitched radio chatter from my tweeters, 

try cables, and TRYT unplugging that darn HDMI cable.

DO they make a better shielded hdmi cable for this , or am i just doomed to unplug when listening?

im in the boat with you, .....lets share the oar .....we will figure this out, there are some very sharp people iim here. They have helped me for quite a many years.

im keeping an eye on this one...........

Yes thanks - all RCA cables connecting the audio. The speakers have 3 prongs in the socket. They do still play with the subs unplugged. I'm going to run through these tests. I just can't unplug the cable coax at the moment because all of the house feeds off this cable box so I'll start a riot. When I can I will run the tests and report what I find. 

Also when I moved in I had every outlet in the house with new GFIs - would the electrician have noticed if the box /  grounding in the house was off or not necessarily?

Yes agreed thanks many much smarter than I hence the SOS!

@jdm11

unplug the HDMI cable to your tv from cable box.

As articdeth suggested, this would be easier than disconnecting the coax cable from the modem or cable box, but if that doesn’t do anything, at some point I would try disconnecting the coax cable to the cable box or modem.

Also when I moved in I had every outlet in the house with new GFIs - would the electrician have noticed if the box / grounding in the house was off or not necessarily?

Most GFCI’s will not work correctly without a ground. Yes, they make ones that work in situations where a ground doesn’t exist, but if you had any of those, he would have had to install specific GFCI’s for that application. If this were the case, I think he would have mentioned this to you. Hard to say if he would have pointed out any other electrical abnormalities. Some houses that were built in the 60’s contained aluminum wiring instead of commonly used copper. Do you remember him mentioning anything about this to you? Not every house in the 60’s was built with aluminum, but it was more popular during that decade than any other.

Maybe I need to disconnect them all from the amp as well or that doesn’t make any sense?

YES! Definitely try that! If THAT fixes the problem, try plugging them back in one source at a time, and see when the hum starts again.

Are your outlets really grounded?  My house was built in 1962 and most of mine are not. A previous owner replaced outlets with GHI outlets for some reason and they’re NOT grounded! I had to run a new circuit to my listening room.

BTW, have you tried a cheater adapter? That has helped me more than once.