I have some old Adcom separates that I picked up used around 6 months ago. It's a preamp/tuner (GTP-5 something) with a 100 Watt amp (GFA-540 I think). Anyway, last night I was playing around with speaker positioning and noticed in the process (my head was right next to the tweeters) that there is a slight hiss coming out. I don't really know where to start troubleshooting on this (or maybe it's just the norm for this equipment?), so I turned off my cheap cd player (thinking it may be emitting some sort of static), but that didn't help. I then turned the volume all the way up to see if it got louder (which is what my old receiver did), but the noise stayed at a constant volume. When I switched the preamp off, it stopped.

So I'm wondering, where is this coming from? Is something in the preamp circuitry causing a hiss, or is it something weird in my cabling (power or interconnects), or do I need to add a power conditioner, or . . . ? Basically, I've got no real idea here so I'm looking for suggestions. It's not that loud or anything, but now that I've noticed it, it's driving me nuts. Any help would be appreciated.