Luxman 550aii vs Luxman 550ax

Looking to buy one of these used and was curious if any one has heard both preferably in the same system? I know the Leica volume is new and the AX I believe the phono is upgraded? Only using streaming devices but may later get a vinyl rig again. I can get a Japanese JDM version for cheaper but considering the ii available here that is US domestic.

Big upgrade in sound or quite Mynute? 

System will be:

Klipsch Forte iii > Luxman 550?? > DAC DAC HS2 > Bluesound Node2