Bryston 4B3 vs Mac MC462 vs Pass Labs X250.8, OR... GRYPHON Diablo 300?

Over the next few weeks I am organizing in-home demo of  three pre/power amps for my B&W 803D2's, and will purchase whichever sounds best.  I will be testing the following gear, which is based on what's available where live:
-Bryston B173 / 4B3-McIntosh C47 / MC462
-Pass Labs X250.8, if I can get my hands on one (will probably use the C47 pre-amp to test with this)
The Gryphon Diablo 300 is also a candidate.  I've seen some strong comments from others that Gryphon is in another league compared to the others.
My question is, barring what sounds best to me during my auditioning, in general to most people would the Diablo 300 really beat the others in my list?  And, are there any material disadvantages to sound quality considering the Diablo is an integrated vs the other choices?  I don't really care about having separates, but sound is obviously important.
Secondly related to the Gryphon, there is only one Gryphon dealer that is even remotely close to me.  Should that dealer cut ties down the road, or go out of business, does anyone know how I might go about getting service for the Diablo should I require it at some point?  Is that a valid concern?  There are multiple Mac dealers near me so that would not be so much of a concern.

Thanks in advance for any feedback....

Morg111,  totally thinking the same as you.  If I do go Bryston I too will actually go 14B3 for greater transparency vs 4B3.  However when you factor cost of 14B3 and suitable preamp, I can get the Gryphon Diablo 300 for the same $$$.  And consensus seems to be that the Diablo is “in another league”.  Will see how I think  the Gryphon compares shortly.  Also agree I expect 462 will only be marginally better than 452.
To be honest I’m not sure where I fit on the spectrum of engaging/detailed vs warm and non-fatiguing. Although to me being able to listen to music hours on end might mean that the music isn’t quite as engaging. If it’s a little more fatiguing I don’t mind if themusic is more engaging....
Really???  So, this is just awful!!! THIS!!! is what you give for us to go on???  THIS IS JUST A SONIC MESS!!!  To me, this means NOTHING!!!  EVERYBODY wants these things!!!  You need to share what YOUR SPECIFIC PRIORITIES ARE!!!  You are all over the place.  You're like a moving target.  Get your act together and get a better idea of what you're asking this crowd.  Otherwise, you're just a time-wasting moving target. 

LOL...  Yeah like you said in your quote of mine I’m still working on figuring that out..
Looking forward in reading about your audition today.  Happy Listening!
Looking forward to this review as I own a pair of B&W 803 D3 speakers. I’m looking to buy either the Mark Levinson 585 or the Diablo 300.

I found the 585 drove 803 D3 speakers with authority. I ended up turning the volume up on quite parts and was caught out with louder sections (kind of difficult to describe) (I used the track below). Which I liked, not something I’ve heard before. I hoping this amp is the same with a lot more than a 585...

It would be nice if you can listen to- Fleetwood Mac - The Chain

This is a good track to test dynamics.