I ended up buying the Accuphase E-450 (now driving Magico V3's), and couldn't be happier with it. As I was winding my way through the decision process, I heard Luxman's 590, but not in a good setup. One of my reasons for deciding for the Accuphase was simply the dealer response and availability for audition (2 years ago, SF Bay Area). I have since listened to Luxman's 505 on SF monitors, and was also very impressed. I think both have potential, but I can personally only recommend the Accuphase, extremely detailed and balanced, without ever sounding harsh. I am less fond of the substantial heat generated by any of the class A versions, but of the AB designs, the Accuphase is outstanding. I know that I wouldn't ever need all the power the E450 can deliver, so could easily see that the smaller models might well be up for the task as well.