CLASS D

Another vote for AGD. I have the Tempo. 

Agree Ralph's Class D amps would be a great companion.

Take a look at the CODA S5.5, if you'd like Class A to consider. 50WPC in Class A, much more in A/B, and 100 AMPs current delivery. I've not heard them with Klipsch speakers, but many times with Volti Razz speakers where they were a brilliant pairing. I have one that happily drives: Buchardt Audio S400 MKIIs, Clayton Shaw Caladans, Thiel CS 2.3s, and even old school Infinity RS Kappa 7s

If it’s a Box Woofer Klipsch. You NEED JUICE to move that Woofer.

+1 @rajugsw - although the horn’s tweeter and midrange can easily handle flea watt amplification, the less than efficient (difficult impedance curves) woofers are tougher to control without adequate power

For “warm” non- tube amplification, maybe a GanFET like AGD and Atma-Sphere or a sliding bias amp like Krell. 

@moose89 - are you open to hybrid amps with tubes?  

Of course @kennyc . I’ve put Orchard Audio Ultra’s on the Woofers of my Cornwall IV’s and a Black Ice F100 with 6550 Tubes and even the big KT170’s. Excellent results. You get the fast articulate Bass of Class D while getting that "warm & gooey" mids and high’s that horns with Tubes are known for.