Pass labs krell parasound amps

Hello, Looking for feedback on the best sound and reliability of these amps, how do they compare to one another. Looking to spend 5-6k on used amp from these choices: Pass Labs x250.8, Krell Duo 300xd, Parasound jc5 or Mcintosh Mc312.

I have Mark Levinson no526 preamp and Revel 228be speakers and like a very open, transparent sound with deep soundstage. 

Thanks for your response.