SOS - Did something Stupid

well - do I feel stupid... I think I may have did something nasty to my cary slp 98 pre.... Here is the scenario...

Cary is shut off - power supply everything...

My sunfire 5 ch amp has 2 inputs/channel - and they say you can bi-amp by daisy chaining the front channel to the rear channel... Hence, in the front I would go in with the pre & also from the front - out to the rear and connect the speaker wires accordingly to the panel & woofer.... That isn't where I screwed up....

I decided to try to go the other way, but using my sunfire PRE into the remaining rear input and daisy chaining 'backwards' up to the panel.... to try to get my processor for movies & tube pre hooked up (i.e. a poor man's theater bypass).... The idea was - when playing stereo from the Cary - make sure the sunfire pre is shut down and when playing movies making sure the Cary is shut down.... Well, I called Sunfire to ask them about this - and unfortunately I think I got bad advice... They said - as long as the pre was shutdown - should be no problem...but no guarantees if the pre was NOT shutdown.

Right now, all I get out of the Cary is a very loud humm.... When I unplug it and put the sunfire pre back in (replacing the cary) - using the same connections as the cary - the sunfire pre works fine.

Anyone care to comment on the possibility of me blowing up my pre - or could it possibly be something else?

You think I could blow the pre even though it was shut down if a signal was coming into the preamp output?

Hmm - I don't know the circuit topology of the Cary, but I'd think that would have been okay.

Will be interesting to see what the others say...

more info ...

with volume all the way down on cary - I get humm/buzz. the only thing that stops it is mute switch. I switch to AUX/CD etc... I get buzz.... Subwoofer gets buzz too - as it is plugged into second output on Cary - even when Cary is OFF. I unplug the power supply on the Cary - and the buzz goes away on the sub (sub has 2 prong cheater plug on it). I have never had this before.

Could this somehow be a ground loop? I just don't know how I got it all of a sudden.... More: I did move some things around... and I have completely unplugged the TV/cable box etc....

Thanks for responses... Tim.

Well - crisis averted... Seems like the umbillical cord that connects the power supply to the pre either was touching something - or has some kind of short in it... I went down again tonight - and left the sub on low so I could control the hum and started picking up wires... as soon as the hum went away - I knew I had the culprit.... Whew!!! just glad I didn't fry anything....Guess that is a cheap lesson..... Needless to say, I am not messing with it - and for what it is worth - it didn't work anyway....although it seemed like it should have...