MF
Really, 4 pages of consternation on what is obviously mis spec'd isolation devices and you're still trying to rationalize why they are OK for your system?? Worried about the cost of an electrician ?? PLEASE. Get your guy over, bypass the crappy isolation and get on with it.........
Yes. He needs to install dedicated lines with none of these isolation gizmos. After some period of time he will then have a baseline for sound quality. At that point he can try adding them back and find out if it helps, hurts, or has no affect.