well, a boss ds-1 with an overdriver(zw44) . That combo can make a really nice distortion set up.
maybe just an overdriver will do the trick. How old are the tubes in it? may play around with new 12ax7s to see if you can't get something more that you like, if you do get some 12ax7s electro-harmonix or jj are both pertty soild brands.
i'd play the marshall before ever getting one. Evrey marshall i have played i didn't like much at all,simple put i hate marshall and feel that they are totally over rated P.o.s. amps .
Saying this i will say that sound is extermly subjective and it is very hard to offer good advice because someone can't just say "you'll love the way this sounds or this pedal is the one for you" it . So in short screw everbody else because they aren't you and dont like the same things as you, play all the stuff you want first hand, it maybe hard but it you are much better off knowing exactly what you need .
i played a digitech death metal today, it gave some alright distortion but it was a bit noise, and out of curiosity i plugged it into a marshall avt 50 combo and it was ok until i turned the pedal off.
yeah i'm not big on marshall either. I actually like fender amps, but then again i'm more of a fusion/rock guy than full blown metal. Either get yourself a good pedal and a dc unit so you can plug it in the wall or get a new amp.
I owned a Hot Rod Deluxe for a while - great amp, awesome cleans and great bluesy overdrive. But, it's not a "metal" distortion amp, and there's nothing you can do to it to change it. If you want a more metal distortion, you realyl should be looking elsewhere...