What does EMI or RFI sound like?

It's dawned on me that I have some pretty respected line conditioning gear in my system that wasn't cheap to purchase yet I don't know what EMI or RFI 'noise' sounds like . . . My Equi-Tech and Foundation Research line conditioners both claim to remove EMI/RFI but I haven't tinkered around with listening with or without them in the playback chain. In case you're wondering, the Equi-Tech 2Q is a 2,000 watt power transformer weighing 80lbs and provides 'balanced power' while the Foundation Research is a bi-directional filter. I have my CDP pluged into the Foundation Research which is itself plugged into a digital recepticle on the Equi-Tech unit - kind of like 2 sets of EMI/RFI noise supression set up daisy chain like. . .

Any help would be appreciated.
RFI (radio freq. interference?) means that you hear radio stations through your speakers - your system (interconnects usually I believe) act as an antenna. Not sure about EMI
Lak - my Equi-Tech unit (which everything is plugged into) in on a dedicated 15A circuit.

Musicslug - that's what I thought but wasn't sure. Keeping short interconnect lengths probably helps prevent it.

Any other people's thoughts?
Radio stations in your music are the extreme.
Mostly, RF is a high pitched white/pink noise in your sound that generally messes-up high frequency sound reproduction, particularly in quiet music passages.
The introduction of a good line filter eliminates the noise or drops it well below the "noise floor", giving you a much quieter, "blacker" background.
I thought the Equi-Tech 2Q requires a 20-amp circuit?
I’m glad you are using a dedicated line that will help in a lot of ways, although that doesn’t answer your question.
Lak - yes the Equi-Tech 2Q unit is a 20amp circuit but it is fine if plugged into a 15amp circuit providing you don't try and put a 20amp load on the 15amp circuit it's connected to. . . so far so good.

Any other ideas on what Electro Magnetic Interferance (EMI) or Radio Frequency Interferance (RFI) sounds like . . . ?