I really like my Plexitone, but I don't know I'd call it a Marshall in a boxIf you have an amp with strong mids look no further than the Carl Martin Plexitone. It´s the reigning champ of hot-rodded Marshall tones in a box.
Marshall Jackhammer does a good take on the high gain Marshall sound. And it's dirt cheap too.
This should be a stickyDistortion is like barbeque sauce. They are almost all good, but you have gotta actually try them yourself to see which one you prefer.
I haven't heard the Jackhammer, but what you described above made me sell the Shredmaster.The pedal is very bass-heavy but can be adjusted. The overdrive setting is very useful and has hi-gain - the distortion setting is a little muddy and hard to use.
I'm looking for something that can do an over the top, high gain Marshall crunch ala Jonny Greenwood and his Shredmaster. I'm considering the Suhr Riot, Emma Reezafratzitz, Crunch Box, and Box of Metal as now. Any input would be appreciated. Thanks!