Any advice? Parasound A21, Ayre V5xe, Benchmark AHB2, or Bryston 4B3?

I have an all Ayre sysrem... all of their components sound best when you use them in balanced mode. ..never had any issues with any of their stuff.  Recommended

I have owned an A21 since January and only heard it through my Martin Logan speakers, so cannot compare to other amps/speakers as others here can.  I can say that my amp does not run hot . . slightly warm only . . but I have it open to room air and would recommend that.  

For that price range, Parasound has an updated model with more power, the A21+, which might be a better comparison to the other models you are looking at.  Normally $3,000, I’ve seen the A21+ on sale recently for about $2,500.

AHB2 has the most resolving power of the amps mentioned.. can’t believe someone stated otherwise. 

my guess, just an educated guess, is that someone who has chosen harbeth compact 7’s are not really into having resolving power at the expense of musicality and coherence

but op, you have the input you seek, benchmark certainly makes a good amp, and has its supporters

good luck making a good choice

I think the best sounding product between you options is the Ayre V5xe.  I have bought equipment that was driven by that amp.  It is built like a tank and Ayre gear sound incredible.  It is best when in a fully balanced system but is tremendous in any scenario.  This assumes the amp is in great shape.  If the amp is not in great shape, I would lean toward Bryston.