How would you compare Ayre to Parasound?

Before buying any Parasound product especially the JC1 amps read all the reviews about build issues ..Well documented in this forum.Given your short list..Ayre is a no brainer

Yes indeed missioncoonery...All Ayre equipment should be run balanced to hear what it is capable of. The single ended connection is only there for convenience. I also recommend you using balanced operation with phono into their preamp. Ayre amps are at the highest level of performance. Their service is impeccable should you need it. I have only used them for upgrades and modifications...my Ayre stuff is bulletproof. If you are going to use Vandersteens, you should know that the vast majority of Vandersteen users have their speakers connected to Ayre amps.

There are high end manufacturers who equal the service and civility of Ayre, but no one exceeds it.

I have no experience with Parasound, but I have heard all of the Ayre amps and they are all excellent within their respective price ranges. And yes, they need to be run in balanced mode for best performance. Depending on your taste, there are other amps you may like better, e.g., I prefer pure class A amps to AB amps, hence I opted for the Lamm M1.2 hybrids, which run in pure Class A and have one 6922 tube each, over the Ayre MX-Rs.

But Ayre's preamps are among a very few that are the best available at any price. I have the K-1xe, which is great, and have listened several times to the KX-R, which may be the best of the best right now.

"vast majority of Vandersteen users have their speakers connected to Ayre amps. "

Baloney! :-) There are tens of thousands of Vandersteen speakers out there and Ayre's entire production wouldn't equal a small percentage of that total.

Ayre and Vandersteen are both great companies but your statement is simply hyperbole. :-)

A few years back, I bought a pair of JC1's for my Vandersteen 3A Sigs I had at the time. I was using a Aesthetix Calypso preamp in a all balanced system.
I did not like the Parasound sound with this combination. (I actually invited some knowledgable audio friends over and they agreed) No doubt, the JC1's are powerful but in a muscle car kind of way. They do not offer up the same kind of holographic imaging nor the soundstage depth. I switched to a Ayre V5Xe and the sound was definitely more to my liking. However, I found the Ayre a little light in the bottom. I then switched to a Theta Dreadnught I in a 2 channel configuration. It provided the same great mids but with a better bottom. Maybe not quite the beautiful imaging of the Ayre but wonderful overall.
I know the JC1's have received a lot of good press but I honestly believe if you want the absolute best out of Vandies, use a no feedback amp. (The JC1's have a moderate amount of negative feedback at about 28db.)
I'm now looking to purchase the Aesthetix Atlas amp which has built switchable 6 db filters required of the higher series Vandersteen's.