Caps going out?? Whats this noise...

I just realized that I have some serious white noise similar to the noise you get when listening to the radio in between stations. The noise only comes from one channel, and only when my passive pre amp is turned off and my amp is still on. The noise is there with only my speakers and power cord connected to the amp (disconnected the rca's to try to locate where the white noise is coming from. Again, there is no noise when the pre amp is also turned on...