Luxman 507/509

Martinol, if possible please audition the 509X and 590AXII (or 507) with your Dynaudio Heritage. I find the L-590AXII to sound splendid in my system with Marten Duke 2. The Class A of the 590AXII imparts a slight warmth to the sound which gives an organic and real feel to instruments and human voice without sacrificing too much slam and dynamics. It's a rather neutral sounding amp.

OP -- you should consider the 550 and 590 models as well. They are quite similar to 507/509, but IMO add a bit more warmth and texture to the sound owing to their ability to operate in pure class A further than the other models.

Just to say thank you very much for your answers, very helpful!

The two areas where Luxman steps up/down seem to be power supplies as well as output transistor pairs. The 509 with 4, 507 with 3, and 505 with 2 pairs per channel.

I find the 507 to be quite splendid with my current setup. :)

@erikt 
Very interesting lower than expected class A bias. Thanks for sharing!  I wonder what all that idle power is doing if not class A bias....

@martinol 
Looking at the pics with lids off, the L-509X has twice as many power supply caps as the 507. This might enhance bass slam, and the 509 is not lacking bass slam in my experience!

I asked Luxman USA in an email about the Class A envelope for the new L-509X(which I bought) and the L-550axii I was considering

Here is their response that I got:
" 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)".

Check out audiodrom’s reviews:
http://www.audiodrom.net/en/integrated-amplifiers

I chose the 509X and am not disappointed. Have not found official publication of the class-A bias but based on comparison of the idle power consumption to the 590 & 550 integrateds, I think the 509X is about 17 WPC class A and the 507 about 9 WPC class A.