The m900u mono was exceptional when I demoed it and way better than the 509x which I had demoed first that same day in the same store (TAD ME-1 speakers). Though, I am not sure if the Luxman in stereo has enough power for the Magico S5 V1 for a big room.
I have recently bought the CODA #8 ($6.2K) and it sounds a lot like that Luxman m900u. I drives my hard to drive Thiel CS3.7 easily and likely your Magic S5 V1. However, since you are willing to go to $15K MSRP you should consider the CODA #16 which is the higher model from the #8. The CODA is American made and likely offering you more value for the same price vs the imported Luxman.
Not a fan of MAC's.
I have recently bought the CODA #8 ($6.2K) and it sounds a lot like that Luxman m900u. I drives my hard to drive Thiel CS3.7 easily and likely your Magic S5 V1. However, since you are willing to go to $15K MSRP you should consider the CODA #16 which is the higher model from the #8. The CODA is American made and likely offering you more value for the same price vs the imported Luxman.
Not a fan of MAC's.