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.
lowrider57

Showing 4 responses by gdnrbob

@lowrider57 
How expensive was the surge protector with noise filtering? It would seem to be the right way to go, in my opinion.
For $750 you would be done with the problem, rather than adding another component/layer. Even better if you can buy yourself for less.
Your electrician seems to be a good guy, if he lets you provide materials.
Though, if you let him install the brand he offers, then he will probably stand behind it should anything go wrong in the future. I'd ask him why he thinks his brand is better than the less expensive ones.
@lowrider57 
Don't let it get to you. Your electrician probably did everything to code.
B
@lowrider57 
That is good news for your wiring. As I said, your electrician seems like a stand up guy.
B