I have two intereference sources in my shack - the CRT's and the 4 port
hub.

The CRT intereference occurs on harmonics of the line frequency and if
one appears on a wanted signal, I go into Properties, Settings,
Advanced and shift the monitor to a new frequency.

The LAN into my hub is 100ft long and radiates a variety of noises and
the 100MHz hub is much worse than the 10MHz hub, so my only workaround
here is to swap hubs if the occasion demands. The DSL is not a cause of
any noises, just the stuff distributing it!

Brad.