By branch I assume you mean outlet on the same circuit? For all the subs I've used, the 350v1, ep500, ep600, and now 350v3', they have always been plugged into an outlet installed in my riser which is on the same 20amp circuit to the HT room

I have never heard this noise until now and nothing has really changed. All my other audio equipment is hooked up in the AV closet to the tripplite, except the Odyssey amps straigh to the wall.

No other products, blenders, refrigerators, microwaves, etc. are on this circuit, branch, or tree.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85