Answer my own question...lol.
From Michael at Ayre:
With the AX-7 upgrades, we added some capacitance on the AC and the DC sides of the circuit, we improved some voltage regulation that lowered some noise that was occurring in the rectifiers. Overall the small changes we made added up to large changes sonically and a significant improvement in performance.
I'm on the schedule :audiophile:
I have to say; even though it took a few days, to acclimate to. I am really loving, the AX-7 and PMC pairing (the QB-9 DSD doesn't hurt, one bit, either). Based on my experiences thus far: first the K-5xe MP...and now the QB-9 DSD and AX-7; I am a BIG fan!
Might have to look, at moving up the Ayre line.