-> I just saw an 800 for $475 or so.  Now that you mentioned what you
-> just mentioned, I'll remember the distinction (reverb).  The
-> this-tube-vs.-that-tube parts I've clipped & saved from a while back.
-> I'll have a lot of time to get ready for this one, in any case.
My $.02 on the JCM800 vs the JCM900:
The early JCM800's are starting to become somewhat sought after because
the early models were JMP 70's models with new cosmetics.  The hip thing
is that they are very well made, and all the tube sockets and pots are
chassis mount and not pcb mounted.  The "hot" 800 models sport input
jacks that are over and under, not side by side.
The later 800's introduced channel switching and a diode clipping
circuit which (IMHO) doesn't sound as good as the early Marshall amps in
terms of tone.  Yes, they have more gain (if you need more) but they
don't necessarily sound better. (Again, AMHO)
The 900's don't sound too bad to me, but if you look at the internals
(as with every major amp manufacturer today) they had to make them
cheaper to compete, and unfortunately they went to pcb-mounted tube
sockets and pots.  The 900 has a particularly wimpy output transformer
that is rather infamous for going up in smoke under professional use.
BTW, I recently auditioned the new JCM2000 and it's not my cup of tea,
either.  The clean sound is good for a Marshall, though...
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