Noise coming from subwoofers and centre channel

Hi,

Yes my power strip is plug via 3 prong.

I did the test to plug the equipement one by one, the noise is really introduce when the projector and processor are in action.

OP:  Not sure how portable your projector is, but can you move it close and use a very short HDMI cable?  If that fixes the issue, a better (not more expensive) cable may be a good option.

No it is heavy (JVC-NZ9) it would be complicated...

Highly recommend buying a digital filter for your Cable wire leading into your cable box. Make sure you get one that's male female so you can just avoid using another wire. You can get them for about 10 to 20 bucks on Amazon. There was a recommendation made earlier for $75 isolator but that was crazy. @jetter .

Maybe the recommendation was for a really great isolator but the one I bought solved 90% of the problem. And my cable wiring to my house is grounded. Another problem I had was I have a tube amplifier and that inherently picked up a lot of hum versus solid state when I had one which had no hum.

You could always just buy a dog and forget about everything else.

OP: Well my recommendation of an HDMI isolator is still the best way to go, but another HDMI cable may help and be a cheap solution.

It would really only help if the ground was significantly better... so for sure dont' spend money on boutique cables.  Buy an affordable one that's as short as possible but looks well made.