The super twin at least has a gain + master volume control. If not, you'd be up around 200W before any amp drive was apparent, and the volume boost from a tube screamer would be truly frightening.

The tube screamers are supposed to work best with Fender style amps, which generally have a dip in the mids as their standard sound. Boosting with a mid-rich pedal is suppose to fill that gap and make a Fender sound a lot more meaty (especially with single coils). Marshals are a lot more mid-heavy in character to start with, so a TS makes the sound even more so, which doesn't always work so well (though if you've cut most of the mids on the EQ for a scooped sound, then it will fill those back in).