PrimaLuna EVO 400 v Cary SLI-100

+1 Cary Audio. Look at CAD 300SEI. Single Ended Triode Class A, full on tube experience for your Heresys. Upgrade the 300b to Gold Lion’s, and some nice NOS 6SN7s, Tung-Sol, Sylvania or RCA. Rated at 15 wpc but probably only outputs 3-5 wpc at normal listening levels. I have the high output LX rated at 20 wpc paired with Forte IIIs and KR 300b’s, simply sublime! 
 

SLI-80HS is a great amp, more versatile tube options as @decooney notes above, but is a push/pull Class AB design with more power output. Rated at 40 wpc in Triode mode and 80 wpc in Ultra Linear, a lot of juice for Klipsch. A lower power SET Class A will give you a more midrange centric tube experience.

Both designed by Cary Audio founder Dennis Had, a true pioneer in bringing tube amps back from the SS era. I have one of his Inspire KT-88 Firebottle amps he builds in a little shop after retiring from Cary that runs 6L6, 6550, EL 34, KT77 and KT 88 output tubes with a single 6SN7 or 6SL7 driver tube. Different from SLI-80 as the Firebottle is a Single Ended Pentode Class A putting out only 10-12 wpc. If you find one of these used, buy IT! Paired with the Heresys, you’ll learn what tube amps are all about.

Cary Audio SKI-80 HS…PL Dialogue…both great…

+1 Trivema re the Cary 300 SEI. I run mine with WE 300Bs and the results are wonderful with Klipsch Belles, which I sold last year, and Heresy I, Heresy II and Volti Rivals which I still own.

The bottom line is we can all tell you our stories and what we hear...    But your hearing and listening room may not even produce what you want to hear from our equipment if in your room...  The bottom line is try and go and listen to a few and see if you can bring it home and try it.. Not Until you hear in your own space will you know if tubes are for you...And listen to what others are saying about tubes and try and get close to best tubes when you listen to  first time..Try and find others that knows these units you are thinking about and chat with them a while on their tube selection ....I was lucky enough to start with Raven Audio and owner Dave knew his machines so well and I explained that I had tinnitus and he would send me tubes to see what matched my hearing and give me best quality sound..I had Osprey for 5 years and Dave over those years shared with me some very nice tubes to keep me happy ..Like anything you purchase over time you will get tired of it and want a change and nothing big but little detail will spark your hearing again ..Just a change of tubes weather power tubes or pre amp ...just 2 pre amp and what a change can make...But if you get  hooked with tube amp sound chances are you enjoy many years of sound you never heard from a solid state...But remember not all songs play through tubes as they do through solid state .. I find tubes break down a song and segregate sound to speakers and solid state keeps it more tighter in sound..This is what I hear from tubes vs solid state..  I also find that some songs I luv and using KT88 tubes they are to airy and need say a 6550 power tubes ..Nothing is perfect ... + / _ no matter what you listen to..

@trivema ...Different from SLI-80 as the Firebottle is a Single Ended Pentode Class A putting out only 10-12 wpc. If you find one of these used, buy IT! Paired with the Heresys, you’ll learn what tube amps are all about.

@mattsca If you want any one of these amps noted by @trivema  , feel free to message me, my colleague with the Hersey speakers is thinking he is going to put his Inspire by Dennis Had Firebottle amps up for sale on USAM including - Inspire 300B, Inspire KT88 amps. Also he still has a standard Cary SLI-80 that will be listed too. The Klipsch Hersey 4s will be listed too. He's stalling a bit, and loves all of it, would love to keep it all - but can't. He had to change his room and went to a basic integrated setup for his family, and making life changes. Feel free to msg.