Will report back in a few days on its effect in my system with strange mains, even through I have a Radial circuit I get humming transformers (DC?)
This has always confused me because, unless you've done differently, most folk will have their new radial fed from the same CU feeding the rest of the house. Even on a split load CU the neutrals and lives will be pretty much shared. My central heating boiler makes a couple of transformers buzz when it fires up - it's on its own MCB and on the "other" side of the CU to my hifi sockets.
IMHO a dc blocker would be needed for me (and maybe you too) to get rid of the buzz. I could put a BMU in there but assume I'd still need the DC blocker otherwise it's likely the BMU will just buzz instead.
I'll await the Doc's thoughts though....