Abyss ? Luxman 550aii ?

I'm looking at buying used 1266 Phi TC for around $3,500USD.  I don't have experience with top end headphones and am currently listening to Sennheiser hd 650's or sony MDR-Z7M2's powered by a Luxman 550Aii int. amp headphone jack.

Does anyone have experience buying abyss used?  Does abyss provide good service or repair?  Does anyone have experience with the Luxman 550aii compared to dedicated headphone amps?  How about the Luxman paired with the 1266TC?

Any suggestions, comments, or opinions will be appreciated.