Noise problem, can someone explain ?

[Inconnu]

I recently aquired a stereo effect pedal. When I plug 2 amps (one to each outputs of the pedal), I get some backround noise not heard when only 1 amp is used. Why ? what can I do about it ?

[Jaco who?]

There's probably a different ground potential on one amp than there is on the other. Simple fix might be using a common power strip to plug both amps into (also the effects pedal), more complex might be running a wire from the chassis ground of one amp to the other.

[billfitzmaurice]

Originally Posted by Inconnu

I recently aquired a stereo effect pedal. When I plug 2 amps (one to each outputs of the pedal), I get some backround noise not heard when only 1 amp is used. Why ? what can I do about it ?

You have a ground loop, causes and cures explained here:
http://www.rane.com/note110.html