[QUOTE=nat8808;519932]).
As I live in a big block of flats, I also get different switching noises; white noise more prominent, then less prominent, then more prominent in few-minute cycles and then different at different times of day.QUOTE]
At least you should get good immunity from RFI as you are surrounded by a steel-reinforced concrete cage. Remember how the old mobile phones wouldn't work in multi-storey car parks?
Current Lash Up:
TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.