PrimaLuna EVO 400 v Cary SLI-100

To @mattsca if you are enamored by the weight and body elements your MC312 amp and Rel subs offer today on your main system, I think its going to take a special tube amplifier with real iron transformers to capture your attention with your Hersey speakers.  This is where personal taste with trial and error begins.  

A friend of mine with all 3 models of Herseys has been through about ten different lower power SET, PSE Triode, and higher power Push Pull tube amps with his Herseys. All of the best tubes in the world too, btw. Each amp type and design gave its own presentation and result. He loved them all for different reasons, delicacy, and more.  Many lacked drive, with "tradeoffs" he reports.   Go figure, today he runs a higher power integrated solid state amp for other reasons, yet now realizes some of the differences going back full circle to where he started. Now has an entire room full of tubes to get rid of, fwiw.    

Best of luck on the journey. :)  

It might be helpful to inject some cross-slang here and see if any insightful daydreams come forth.

"Tubular"

I had a pair of Primaluna EVO 400's for about six months running as monoblocks. The stock tubes left a lot to be desired and a change to KT88 power tubes and vintage Cifte 12AU7's helped a good bit. However, they never really gave me that tube sound "wow" soundstage I had experienced with my old Cary 6 Packs from long ago. I sold off the EVO's and moved on to a pair of CJ LP275M's. Those are my keepers.

you can give a try our LM-219IA PLUS 

i currently have the evo 400 tube preamp and amp; both great choices; punch way above their weight class and have great technology built in....i have run them with my hersey 3 and loved it...75 watts is more than you’ll ever need to drive that speaker....and easy to tube roll with the evo 400 also...i used the same set up to power my AK6 Klipshorns and they sounded incredible as well; however albeit NOT reference quality, but still very good......both sets of those speakers are now in storage and I am running Wilson Audio SashaV with the Prima Luna gear....and this weekend, will start with mono blocks....as i just purchased another Prima Luna EVO 400 tube amp.....until I can get the Audio Research 330M’s, this will do ok...i’d say with both your speaker and amplifier choice, you are getting HUGE value for your money....way above what you spent.....you are toying with $20K performance in a much better valued system...Go For It....oh, and btw, I have had the 400 amp and preamp for four years now; only have about 120 hours total tube time on them but they sound great; only rolled a set of Tung Sol's through the amp and it did give me more sound stage....have fun with it...no system is ever and "end all to be all" system....it's the nature of our hobby and our addiction....bigger and better...always chase the dream....one can be content for only a period of time....live a little!