Re: hardcore/metal tone from a DSL?
A friend of mine who plays in a hardcore/metal style band plays the DSL100 through a 1960A marshall cab using an SG and the tone is MONSTROUS. I think that ALOT of the marshall tone is in that cab.
Vintage 30's are great speakers as well, but i dont know how they would sound in that mesa cab vs. the marshall cab. Try rolling your tone knob back a bit, turning the gain down, bass to taste, treble and mids slightly before 12'oclock. Volume up of course!
If the amp just sounds fizzy compared to its normal self, and you've been playing for quite a few months with it, the tubes may need changing. These settings should help though. The cabinet is one of the most important components when it comes to getting a good tone, especially because it is the piece of equipment that undergoes the most vibration/resonance. Maybe the way the marshall cabs are built, eventhough they are smaller than the Mesa cabs, it may contribute to the way that they resonate and contribute to the sound.