New HD130 owner! Some questions...

Hey guys...great forum here! I dropped by my local GC today at lunch for some other things, and found a Music Man HD130 head for $399 sitting in the back room. Very clean, but it has been re-tubed (with EH EL-34s). Sounded good through the old Bandmaster 2x12 they had it plugged into, but I'll give it a shakedown cruise tonight at band practice and see what happens.
This one also has a single 12ax7 tube, which I assume is the PI, since the amp has a solid-state pre-amp section, right? So what date-of-manufacture range would that put it in? Anything else I should know about these? How do they sound through a Marshall 4x12 cab (@ 4-ohms)?
Thanks for your time and help!
Best,
Mike in Baltimore

Great amp you got there Mikey!! I know, I have one too! Your amp date cannot be exactly determined, but it was built some time between 1974-1977. The tube PI falls between those years. I play mine through a celestion/eminence legend 4x12 cab and think it sounds fantastic. Of coarse, this amp is a LEO FENDER design, so it will tend to sound more "Fender" than anything else, but it crosses a bit into "marshall-Like" territory. The EL34/6CA7 may have something to do with that. I play some Aerosmith, Zep, and even AC/DC with it and though not exact, it's close enough. The celestions might even take it closer to that Marshall territory too. I use a THD Hot plate with mine and when the amp is dimed (in LOW power) it simply cannot be beat. Huge sustain, and rich tone. One thing I suggest to you, is to become *very* familiar with the biasing procedure for the amp. I recently came across a guy who was very unhappy with his HD130 after a tube swap (JJ EL34L). His local store installed the new tubes and biased it like other "normal" Fenders. He rebiased it himself (with the info on this site) and fell back in love with the amp and loves those JJ's. Keep in mind that their are some HUGE voltages in there (700+) that can kill!! Congratulations!!