He doesn't want to hear what's been scientifically proven from you, me or anyone. It is what it is. As long as we're all happy with the results.
FWIW - I used the 3M EMI/RFI sheet I stated above + copper in my music server, seemed to work well.
The advice given to me was to use aluminium foil for the shielding to stop switching noise from affecting my electronics. The foil made a huge difference to the noise floor, which was already low anyway. It also reduced the sibilance on some female vocals. I reported this as an effective tweak. Perhaps copper foil would have been better, but the difference with aluminium foil and aluminium tape was immediately noticeable. It was explained to me that this would stop the power supplies and filtering in the electronics, especially very low voltage phono stages, from being overworked in trying to filter out this type of electronic noise.
Due to all the comments on the beneficial effects of copper for shielding, I have now decided to experiment with a combination of copper foil and aluminium foil in a sandwich arrangement with an intermediate layer of Tygon polymer to act as constrained layer damping. I also have lead sheeting which I will add in another layer with an intermediate layer of woven plated copper/conductive Nylon.
Thank you all so much for your advice.
I will report back on any beneficial effects soon!!!
On another note, I do agree with the notion that interconnect cables should be separated from power cables by as much distance as possible. I have three additional 20 amp dedicated cables that supply power to my system directly from the fuse box. They travel down the wall behind the electronics. I will be looking at some shielding for this wall also and hopefully this will make further improvements.