okay i got a Peavey Rage 158 and sadly a MG100DFX but anyways I was wondering after seeing somewhere in guitar world, that this one guitarists uses another amp head as a power amp. Could I do this on my marshall and peavey???
Take a cable from the headphone output on the Peavey to the Effects Loop Line IN on the back of the Marshall and that should work. It might not sound too good, but you shouldn't be expecting a huge leap in quality anyway, it'll just be the Peavey sound but louder.
I'm currently running my Engl tube preamp, using the power amp of a POS solid-state Crate practice amp, using its speaker output to run into a 4x12 cab, and it sounds awesome. If you're happy with the sound from the Peavey, the MG should amplify that sound fairly "transparently," if connected as described above.