Pass labs krell parasound amps

@OP. The X250.8 is a great amp. It should work well with your Levinson pre.

One other brand worth looking at is Sim Moon which might fit your sonic preferences well.

Nelson Pass has a long history of designing reliable  & wonderful amps.  I owned a 
Threshold 4000 for 25 years before selling it and buying the X250.8.  Yes, they run hot & yes, the X250.8 does have the "Pass " sound, which makes it very easy to enjoy and live with.  Once you own it I cannot imagine an unhappiness UNLESS you are one who continues to compare A to B....on its own it is great....additionally, you will be hard pressed to find a company with better customer service, though I doubt you will ever need it...

Personally, I would stay away from Krell until they get their house in order due to the loss of one of their founders.

Pass and Parasound are bullet proof with excellent customer service.  I have no experience with Mac.

I moved from a Benchmark AHB2 to an Accuphase P4600. Yes the Benchmark had a sharpness in the lower treble but also a powerful base. It’s still a real bargain if paired with the right speakers that are very warm. Even with my Harbeths I still found it a little too cold for my taste The Accuphase is just very musical, live and refined. But expensive. If Accuphase is in your price range please audition. Plus their Class AB amps run only slightly warm. 

Of what you listed I would choose Pass labs.  Excellent products and support.