The amplifier used is an Adcom GFA-545. The preamp used is a Harman/Kardon PT2300, both units are older (Adcom from the 80's, H/K from early 90's I believe).

With this preamp, which I just picked up, it pops when I switch between sources. It also has a Pre-Out control to select Off, A, B, or A+B (it has two preamp outputs). If I toggle between these controls it also pops.

Now I am used to the pop of the old Adcom when I switch on its power (so I leave it on all the time), but with the Lexicon CP-3 I was using as a preamp, the pop upon turn on/off was very minimal and there was no audiable sound between source switching.

Does something cause these noises (oxidation of internal components, capacitors failing, or something of the like), or is it just the vintage of these electronics?

Thanks for any input.

I just get annoyed that these 'nicer' components do this, but these cheap Kenwood receiver I have from the mid 90's does nothing of the sort and it was $250 in the mid 90's.....being cheap and made in China (back when that still meant it was crap).