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

I already offered to leave a deposit to bring the Gryphon home for a demo and dealer said they don’t do in-home demos, full stop. And I’d need to lug 180 pounds of speakers to the shop (which is not local to me), risking damage especially with exposed tweeters. I will go back for a second audition, and probably proceed with the Diablo even if everything isn’t 100% perfect to my ears with the speakers they have on hand (I will test using Sonus Faber speakers next, instead of the 802’s. If I end up having to sell (hopefully not), I know I could be happy with a less advanced but still very all-round capable and highly enjoyable Bryston 14B3 based system. At least, that is my thinking at this point.  

I see. This ever-present power and will of the Diablo that go thru everything create this complicated impression.
They say it will drive almost any speakers. Maybe so but this doesn't mean it will match well with them all.
If you can afford buying and then selling if you have too, that's good, it gives you more space and time to make the final decision. 
 

Best of luck and great listening with the Diablo Nyve! I read a review on it thanks to you. Truly unique design. Like how the first 10W is class A out of it.

Okay, I've completed a second audition of the Gryphon Diablo 300.  As I was prepared for the type of sound to expect, from the first audition, the results were far clearer for me this time.  I'll be proceeding with purchasing the Diablo 300.
I started testing driving the 802 D3's again, just as a baseline from where I left off last time.  In the end I didn't feel the need to switch out the speakers.  The huge dynamics, timing and drive, impressive 3D soundstaging, very solid and well developed midrange, and excellent bass that most all reviewers / posters have commented on were all there, and were all very impressive.  I believe that a good portion of the midrange quality is derived from the internal DAC module, with mids being well "grounded" as one pro review put it.  I noticed that this quality was not there when using an external (albeit much lower-end) DAC. 

Everything was very, very impressive.  At the end I even threw some poorer quality recordings at the Diablo to see how badly things would go, and it totally surprised me by making them sound great - even highlighting vocal details I'd never caught before on these crap mixes.  I thought the incredible amount of detail would surely make the Diablo tear these songs apart, but instead the songs really did take on the feel of a live performance.  These same recordings have bordered on un-listenable on my current rig at home.  It's paradoxical that a system that is so transparent and revealing in detail can still make poorer recordings/mixes sound musical and enjoyable - this is not typically the case.
I think my first audition went off the rails a bit for a few reasons:  1) Up to that point I'd been used to auditioning gear in my home.  While it is obviously better to test in your own space with your own gear, the mental shift to testing in a shop was also jarring, and 2) the first audition I used my own speaker cables for part of the test, and I noticed after I got home that one of the spade terminals had become slightly unscrewed, which would have slightly unseated the compression contact on one of the terminals, and 3) just the sheer capabilities of the Gryphon was not something I was expecting.  During the first audition, it felt a bit like seeing a 3D movie - stunning, but not an experience you necessarily want all the time.  However, this time around, I was just impressed and enjoyed the music.
While I'm planning on proceeding, the only slight concern I have is with regard to service, should I ever need it.  Shipping the unit back to Denmark for repair will not be cheap, however my guess is that this may only happen once in its (or my) lifetime.  Chalk it up to cost of ownership.  The other concern is that there are only three dealers in North America.  If Gryphon decides (again) they want or need to pull out of N.A. sales, there won't be any way to get service.  Gryphon states they do not provide any direct service or communication to customers; they direct customers to their dealers.  Finally, Fleming Rasmussen has now retired, and as Gryphon is a very small company (say compared to McIntosh or Bryston), I'd hope that they have a strong future even without their former leader who was heavily invested in all aspects of design, and I expect in other areas of the company operations as well. At the end of the day these concerns won't stop me from proceeding, but they are certainly considerations.  Their headquarters looks cool but it is tiny - you can see it from a distance on Google St View!  I guess these things just go along with a bespoke brand like Gryphon.