Cool, Congratulations, and thanks for posting Got the LB550, too - rather good deal, though no anywhere near as good as yours - and, most important, great amp! Played the ABM500 for quite a while, but the LB550 definitely has a different sound (that suits my style even more). The same amount of massive bottom end, but somehow much more ... hm ... "creamy", can you say this? Sorry, my English is long past it's best days
And the LB550 also has a much more pronounced, clear high-end. It CAN sound very "vintage", but in my opinion it's also really easy to dial in rather modern (rock) sounds, though it never gets too over the top ... Still sounds pleasant with extreme EQ settings.
Amazing amp, I play it in a 90s-style-thrash-metal-band, but it delivers a huge range of (tube) tones ... Actually, I'm quite impressed - played it for rehearsal, have yet to gig it. And it can get DAMN loud, have to compete with our guitarists' two tube-stacks - we aren't one of these quiet, disciplined bands at rehearsal I've got it running with the gain at about 60% and the master at about 40% - it's still got plenty of headroom, but is already more than loud enough Without any dropouts or similar problems that I experienced with several other digital power stages.
Just ordered the VS212 cab, too, as with my last 12/8/tweeter cabs I found I liked the tone most with the 8s and tweeters off. So the V212 should be a good match, and at 8ohm can still be upgraded to 2 cabs ... And, admittedly, it just perfectly suits the LB's look