"As a direct example, some feel that the Luxman 509X class AB at $9.5k sounds better than the Luxman 590axii class A at $9k. Can’t get much more absolute-busting than that. Same company, both integrateds with same features, essentially same price, both current products."

===

I thought that too (and I own the L-509X), but did you know the L-509X is both A and A/B? It delivers the first 6 watts as "pure" Class A then transitions to A/B for the rest of its rated output.

I confirmed this with Luxman USA during a discussion of the L-550 (which is also a hybrid A, A/B, not just A)

Quote from Luxman USA email

...The Luxman L-509x is an excellent amplifier. It is considered “top of the line” and most recently introduced Luxman integrated amplifier model. It features circuit and construction details/refinements not present in (earlier introduced) the L-550aXII and L-590aXII.Just tossing that into the pot for consideration.

L-509x is biased such that the class-A operational envelop approaches 6 watts/channel into an 8 ohms resistive load. At lower (or higher impedances) class-A operation transitions to class AB at lower output. (i.e. near 3 watts/4 ohms resistive load)