Amp to Pair with Revel F228be

I had the Pass X250.8 on my list as well but no chance to demo,so went with my first choice ,the JC5 and couldn't be happier .

I'm tempted to save a couple grand on a demo jc5 with warranty, but have read great things about the pass amps.

Here ya go!
https://avahifi.com/collections/power-amplifiers

I have the ATI6003 and it drives the F228Be great. But I can see you are going higher up the hi end food chain! 

mf612 OP Amp to Pair with Revel F228be

Quite a hard load on amplifiers, have to be a good one to get the very best out of them.

Stereophile’s Revel F228be measurements
"The impedance magnitude remains below 8 ohms for the entire midrange and bass, with minimum values of 3.42 ohms at 98Hz and 3.55 ohms at 290Hz (fig.1). There is also a demanding combination of 5 ohms magnitude and 39.5° electrical phase angle at 390Hz. While its nominal impedance is specified as 8 ohms, the Performa F228Be would work best with an amplifier that’s comfortable driving 4 ohm loads."

This would be very nice integrated for them, if he’s still got it for sale
https://www.audiogon.com/listings/lisa8830-gryphon-diablo-120-solid-state?refsource=hifishark

Or if you've got the bucks, it's bigger bother.
https://www.usaudiomart.com/details/649572544-the-gryphon-diablo-300-mint-condition/

Cheers George

You've got three completely different amp sounds on your short list.  First, the Revel are very neutral and very high resolution speakers.  I really loved them when I heard them.  That being said:

Pass Labs - has a slightly colored sound that gives you that FET based texture.  It has very good resolution, but the sound seems "controlled" in a way.  Hard to describe here.

Sim Audio - I have heard these with B&W D3 speakers (which are high resolution like Revel).  I didn't care for them.  They are colored in a sense that they present a "tangy" sound to the upper mids and highs.  This is also hard to describe.

Parasound JC5.  These are probably the most neutral of the three, but are voiced very slightly on the warm side.  Midrange is extremely clean and amp has lots of dynamics, but the highs are slightly dry and probably slightly rolled off.

It really depends what kind of sound you want.  For music, I would go with either Pass Labs or Parasound.  I would probably slant towards Pass Labs because Parasound has that dryer sound.

For Home Theater, I would actually go with different amps.  The suggestion of ATI AT6003 (or any 6000 series) would be much better for HT because it's a very high resolution but very neutral and uncolored amp (you do not want colored sound for HT).  The better, but more expensive choice, would be the Gryphon amps that George recommended.  Extremely high resolution and awsome sound, but does not have that color or texture of Pass Labs.

Once again, it depends on what kind of sound you want.