popping noise when turning on amp/preamp

Just to establish a few points, first, the pre amp should be turned on first and turned off last (your preamp should always be in control of your amplifier). That said, it sounds like you have a problem in one or both of those two components. If you use the "pre-outs" of the cambridge (if you have them, and I believe that you do), you can substitute the Cambridge for your preamp, and if the humming and buzzing persist, you will know that the amplifier is the likely culprit (a qualified tech should then be able to provide a repair without too much angst), assuming that all of your connections are firm (go over all of them just to be sure). I hope this helps, Happy Listening

thanks. i thought of trying just what you suggested after i started the thread. using the cambridge as a preamp, i heard no buzz or popping. so i figured it was the bryston preamp.

but then i decided to use the same interconnects i was using on the cambridge on the bryston. that took care of the problem! in other words, the interconnects were the culprit.

interestingly, the interconnects i was originally using on the bryston were more expensive. the interconnects that ended up sounding good were cheapo ones you get with any stereo system.

Perhaps shielded vs. unshielded interconnects! Try to route your more expensive (culprit) differently and away from power cables... and see if the buzz goes away.... or stick with the cheapo ones if you hear no difference in sound....