Hissing sound when I turn on preamp. Please advise

Another way of describing this sound is the sound you may hear from your speakers when you turn the volume up on your system with no music playing.
I have never had this problem until I recently replaced/downgraded my speaker cable. My Snell Type D speakers have always been wired in a bi-wire configuration.
I recently sold my spkr. cable and for the first time I ran a single run.
The speaker cable I'm using is Kimber 4TC. My local audio shop simply took my 4TC and made bare wire jumpers for my Snells. In fact, all my connections with the 4TC are bare wire.
Could the cables be causing this problem or is it preamp related?
As always, thanks for your feedback!
Make sure the speaker cable is not near any power cable. Sounds like EMI. Speaker cable would not cause this but try the above. Also make sure interconnects are not near any power cable.
Take your foot off of the cat's tail?