LUXMAN L509X VS M700/C700U

So, we know this:
Luxman underrated the 590 in a way they have not underrated the 509 or 507. That is, the measured performance of the 509/507 are much closer to published spec.

We don't know why.

I only offer a hypothesis, that the heat sinks can't get the amp past the FTC.

I don't think this is bad, by the way. It is a smart compromise.

I just spoke to my dealer in upstate NY 
He Currently does not have the cl 38 uc but says it’s his all time favorite 
I will audition the 509x soon 

Half the time that I say I’m done posting, I eat my words. Oh well.
Erik, Luxman’s published power specs are confined to the Class A pieces, from what I’ve seen. The 505/07/09 are all A/B, and specified in a straight forward manner. The L-550 and L-590, both Class A, (but later switch to A/B), but only are specified as Class A.
I looked around a little to be sure, this is Stereophile’s review of the now-discontinued M-800A power amp. Also a Class A piece. I’ll not say anything else other than you may find John Atkinson’s measurements interesting. Luxman obviously has reasons for what they do. I don’t know what they are. From what I have seen, the ratings are the same for the non-U.S. models.
https://www.stereophile.com/solidpoweramps/1108lux/index.html

Erik, Luxman’s published power specs are confined to the Class A pieces, from what I’ve seen. The 505/07/09 are all A/B, and specified in a straight forward manner. The L-550 and L-590, both Class A, (but later switch to A/B), but only are specified as Class A.

So, your inference is good, but my inference is not, based on what?

Your hypothesis is not implausible, but how would a neutral third party judge between the two of us?

So, I wrote to Luxman America and asked the question regarding 590 power directly. :)

That really is what I should have done ages ago. I'll post the reply, so long as they agree with me. :D

Best,
E