I've recently acquired an '83 JCM800 4010 (50W 1x12 combo) that I've turned into a head, so it's very similar to a 2204. I'm going to take it in for a checkup soon and was considering having it converted from 6550s to EL34s with the hope of getting a slightly more "classic" Marshall sound. It sounds pretty great as is, but I'd like a bit more compression - it's a little "hard" sounding now. Since this is an '83, I'm assuming that it has higher plate voltage that earlier 800s or JMPs... So, for anyone who's done the 6550 to EL34 swap, what did you end up using? How did it turn out? Did you like the results?