Was helping my folks clear out their garage this weekend, and we came across an NAD 2600A amp and 1700 pre-amp/tuner. My father bought these in the late 80s but replaced them a few years ago with a Yammy surround receiver. Said he didn't want them anymore so he gave them to me. After hooking up at my place, I noticed a crackling (or popping) sound coming from the speakers when I would adjust the volume on the pre-amp. I noticed that the volume dial feels a bit tight, and doesn't rotate very smoothly like the other dials. I took off the knob, and sprayed some electrical contact cleaner on the dial, but it didn't help. I believe the amp is good, and that the problem lies in the pre-amp, but I'm not certain. I'm going to hook up the 2600 to my HT receiver's pre-outs tonite to see if I can isolate the problem down to the 1700.
Any suggestions on what else I could try? I'd like to be able to use the combo in my living room which is only for music since I'm certain they will offer superior sound to the 15-yr old Sony ES receiver I'm currently using. Is it worth taking them in to a shop to see about repairs? Or would I be better off maybe looking for another used pre-amp/tuner combo to pair with the amp? I wish I could just use my receiver as the pre but it doesn't have the outputs.