Difference between Luxman L-550A II & L-507u

I was wondering if anyone has heard both of these Luxman integrated amps, and can comment on the sonic differences. I have heard the L-550A II and the bigger 590 and was very impressed. I'm seriously considering getting the 550, but just read about the 507 and am curious. It's not on audition close to me, so wondering if anyone can chime in (and not just a guess about Class A vs. Class AB, but actual experience).

Thanks!