[tlug] Speaker Noise

[CL <az.4tlug@example.com>]

Can anyone recommend an electrical filter setup or speakers which are 
not easily driven by residual power from a tower system?

I'm running a Kubuntu AMD tower and a diskless HP (WIN XP) Thin Client 
at my desk.  Both share USB mouse and keyboard, DVI screen, and speakers 
through a CPU switch than can be switched with a button or a keyboard 
key combination.

Problem is that, when I switch to my desktop machine, the speaker driver 
magnets are receiving bleed energy from somewhere in the tower (one of 
the two sits about 20cm directly above the top of the tower / power 
supply) and give a constant low frequency whistle that rises and falls 
while I work, changing pitch when I switch virtual desktops.  So, I have 
been working with the speakers off quite a bit, but that has led to 
missing the aural signals I set up so I can catch incoming Skype 
messages ... and the internal intercom I set up so my wife can call me 
to dinner without shouting (can anyone guess which of these problems is 
leading me to ask?).

So, I am looking for a way to either filter the noise or a 
recommendation for a good set of desktop speakers (wired, preferably) 
that are not so susceptible to picking up noise through the magnets.  A 
couple of sites I've checked recommend an 80 or 100 silver / gold / 
platinum-rated power supply which, they allege, are better isolated than 
unrated supplies.  But, since these sites just happen to have a "buy it 
here" page for power supplies I am suspicious.  Other options welcomed.

--
CL