Tube and Valve are the North American and British name for the same thing. Tubes are generally more "vintage" sounding than solid state, though IMO with either type and the right pups/fx you can get pretty close to any sound you're going for. Sadly I'm not into metal so I'm not really sure what the best bet for you would be--Marshalls generally are both very loud and good quality, though you're paying a lot for the name and could get an amp that sounds just as good but with a different name on it for a lot cheaper...just my opinion of course
