I don't really know the amp in question, but there must be a way to get a good sound out of a Strat through Marshall. I have a crappy VS 30R, but when cranked it's quite pleasing to my ears. And a lot of feedback to play with.
Obey the following and thou shall have all the blessings of not-crappy tone:

1.a. Too much bass = muddy sound with no definition.
1.b. Not enough bass = wimpy sound.
2.a. Too much middle = mid-position wah sound, 80's solo perhaps, bad for rhythm.
2.b. Not enough middle = instant thrash rhythm, not enough body for solo.
3.a. Too much treble = screaming, ear piercing sound. The dogs will obey thou.
3.b. Not enough treble = too soft, doesn't cut. Incidentally, similar to 1.a.

The rest is up to your ears.