Recommendations and thoughts for end game speakers and amps

Good morning all. I am looking at Rockport Avior ii speakers. My dealer likes Boulder amps with these but I wanted to get everyone’s opinion first. I will be getting an integrated with HT bypass. Right now I’m looking at the Boulder 866, Gryphon Diablo 300, and the Simaudio 700iv2. Has anyone listened to these speakers with these amps? I’m looking for highly detailed but not harsh highs and mids and outstanding bass as well. Basically a set up that performs fantastic from top to bottom. If you have any other speaker or amp suggestions please let me know. Thank you! 
The Marten Parkers trio are exceptional Loudspeakers
the Diamond edition even better still perfect match for theGryphon Diablo i have heard them both together and on the low side of your  budget.
Rockports are incredible.  There is nothing wrong with them as end-game speakers.  Boulder is brilliant with them.  I might also look at Constellation, Soulution and D'Agastino, but Boulder is safe and it is unlikely you will be disapointed.

There are a bunch of other awesome speakers in your price range.  Vivid G3s, Wilson Benesch ACT One Evolutions, etc... but they are not inherently better than Rockports.  Different and I might like their tech better but it is a matter of philosophy and taste.

   The Magtech has been on my radar for a long time. She was sent to me, sat on my house for a week, did not open, shipped back to Roger from financial issues we had at the time.    Wish she was still here, 

   His setup is simply outstanding, the incorporated woofer with the panel speaker is flawlessly matched for music, unlike some of the other brands.

 Anyway, if you’ve decided to go another route, great!

or try the Sanders sound in home for 30 days!

Thanks for the input and suggestions. When I listened to the rockports they were being driven by Boulders big stereo amp (2160?). All class A. In the short amount of time I spent listening I found myself wanting a little more energy in the highs. Will the 866A/B give me that ? Also I’d rather not spend 15 k on cables if there is a high quality alternative. Along with the other suggestions offered do you have any suggestions for cabling? Thanks! 
What about Nordost on the used market?