Dedicated Line Noise Filter?


I don’t know if what I’m seeking exists, so I’m asking the experts.
I have 2 dedicated lines installed; one for analogue, one for digital. They originate at a sub-panel off the main circuit box. The sub-panel is connected by the hot lead and has it’s own ground including a second grounding rod. There is a home surge protector installed at the main circuit box.

I have passive conditioning on both lines for the components, yet I’m still hearing noise thru the speakers (from about two feet away). I live in a city and I suppose it could be dirty power from the grid.
Now to my question; is there a noise filter that can be installed at the site of the circuit panels? My electrician offered a surge protector with noise filtering (plus EMI/RFI), but was very expensive. So, is there a device that can be installed upstream to lower the noise floor?
Many thanks.
128x128lowrider57
Yeah, he's a good guy. When he saw that I bought the Romex at Lowes, he said "save your money and return it, I'll use my wire n/c.
@falconquest , a couple of questions...
Can an analogue device plus digital be plugged into a balanced power conditioner w/o any digital noise transfer? Example, I know for a fact that my PSA Perfectwave bleeds digital noise back to the mains.

Secondly, what happens if an amp on a separate AC line is tied to the preamp in the balanced power unit?
I can't speak to balanced power conditioners as a whole but my BPT has separate plugs for amps and front end equipment. I would suggest contacting the manufacturer with your question. I also cannot speak to tube gear as everything I use is solid state. You may want to email Equi=Tech with those questions.