Today i tried to "slave" my two amp heads, to no success. I have a marshall jcm 2000 dsl 100 and a Hovercraft Falcon 100. I wanted to try this to attempt to use the preamp of one amp and the power amp of another. I honestly could not hear any difference in sound or tone, in fact all I could hear was the "master" amp coming out of my cabinet.

here was my process:

Guitar-->Marshall---> FX send--> FX return of Falcon 100.

Both amps were hooked up from their 4 ohms outs to the same 8 ohm matamp 2x12. The marshall was the only amp that had guitar tone coming out of it, I put it on standby and could hear a hum coming from the falcon out of the cab. It was clear that it was sending signal to the cab because if i turned the volume up, the hum increased.

I then reversed the process: Guitar--> Falcon 100-->FX send---> FX Return of Marshall DSL. This gave me the same result. Master head produced noise, only got a hum from the slave.

I could be doing this wrong, but this is my first attempt. any advice?
Hang on - you had both amps connected to the same cab? At the same time? Please tell me that is not the case.
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I did. I have a mesa 4x12 also and was told you can run two heads split between the speakers via the multiple ins, or daisy multiple cabs together. Like I said I didn't try but for a couple minutes cause I couldn't get any results, both heads still work after trying them on their own afterwards. I'm guessing whatever info was given to me was wrong based on your reaction. No surprise, considering there is more misinformation on gear these days than solid facts.
Wow..I realize exactly what I did. I didn't have but the one cab at my house today and not thinking I plugged into what I thought was stereo input, but was actually just an 'in, and out'. Ughhhhhhh...I hate myself. Good thing everything was at extreme low volume and only for like 1 minute. Hope I didn't ruin an amp using half my brain...
Since both amps still work you're ok, usually it's a matter of no damage or big smoky mess. Glad nothing was broken, that's definitely what I was worried about reading the first post.
Yeah a buddy of mine had a mig 50's OT burn up at my house. It would have cost as much as the amp almost to replace so it's no more. I basically spent all day reading about slaving heads but don't have half my gear at home, ran down stares not thinking and just started plugging into the only cab lying around, but stopped almost immediately because I knew something wasn't working right.
no real clue why you would want to slave a 100W marshall into another 100w poweramp. if your adamant on doing this, you should probably get a dummy load for the preamp-amp (you can build one easy for dirt cheap) and a ground lift plug for that same amp.

It goes without saying you should always have the amps connected to a speaker or dummy load. The ground lift for one amp is necessary because you'll get a ground loop, which is basically a constant annoying hum coming out of your speakers. But again, youll likely gain nothing by slaving the marshall into the falcon.
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