Ayre DACs can certainly be endgame. I wouldn't be worried about that.
The nice thing about the EX-8 is that it has a pass-through mode which sets the amp to unity gain. A good feature to have since you're integrating it with the MRX540.
Note that the Luxman also has pre-outs which are functionally equivalent to the pre / sub outs on the Ayre.
I used to own several pieces of Ayre gear - AX-5 Twenty, C-5xeMP and QB-9 DSD. All were exceptional. I did find that I gravitated more towards certain types of music genres like classical and jazz when they were in my systems.