I have a four-year-old NAD reciever connected to some very old BIC
Venturi speakers. I haven't used it much recently, and when playing the
radio today, I noticed short bursts of hiss (something close to white
noise) interrupting the program ever so often--at least once per minute.
I chalked this up to reception problems, but it turns out the same
problem is present when playing cd's.

Any suggestions about possible causes of/remedies for this obnoxious
problem? Other than this, there is no indication that any of the
equipment is failing.

For what its worth, there is a history of strange electricity-related
failures (power supplies suddenly going out, outlets failing, light
bulbs burning out prematurely) here in my 1920s-era apartment.

Your help will be much appreciated.