The Wampler Triple Wreck will turn your Marshall into a Rectifier.
That way you can have both Marshall and Mesa in one amp. However, you really don't want any gain going from the amp when you hit the Wreck. It's a complete beast.
Stop by and try these out,and bring that rhodes..They all sound good in front of my jcm 800.But if you want more gain without the annoying mid hump of a tubescreamer and the like,My Tim pedal gives you, well, just "more"..Extremely transparent overdrive..I read somewhere that Paul C. made these for old marshalls.I had a wampler pinnacle deluxe-until I got the bogner red.Bogner is killer,but my fav.transparent overdrive is the tim or timmy.