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.