The Revel speakers are not that hard to drive. They dip just under 4 ohms at the 300hz to 400hz area, but mostly they are 5 ohms or above. However, I feel these speakers can be touchy because of the metal domes tweeters and can easily sound too bright/harsh.
The Pass Labs is a very neutral and controlled amplifier, but it is still a very strong amplifier. I think it would be a good pairing with the Revel speakers. You can get away with the INT-150 integrated (there's one up for sale for $4k). If you can get an INT-250 within your budget, it is basically the newer 250.8 amplifier with what looks like a trimmed down XP-20 preamp inside the chassis. Nice. The INT-150 uses the older gen 1 amp (I think), but it would also be a great solution if you wanted to save budget.
There's a stand alone Pass Labs 250.8 amp on usaudiomart for $6200. Then just add a nice preamp.