Here's a tidbit I found out from Luxman America regarding the L-509X...it's a hybrid Class A,A/B doing the first 6 watts (8 ohms) as Class A.
From an email reply I got from Luxman:
[quote]
...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.
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)
[/quote]
Who would've thunk that?