Luxman L590AX vs.590AXii

I am in the position of being able to buy either the 590AX or the 590AXii. The AXii is 2x the cost of the AX. I listened to the AX through Focal Kanta No2 speakers, which I own, and was thoroughly impressed. My question is this: what improvements did Luxman do to the AXii  relative to the AX that might justify spending 2x the cash on it?

The AX I listened to was manufactured in 2015 and is in pristine condition.

TIA