What amp/pre-amp for my Klipschorns?

Not exclusively tubes. One of the most impressive sounding set-up was NAD monoblocks and K-horns. But that was sometime in mid 80's, and nowdays choices are virtualy unlimited. You might be able to get nice SET amps, or even push-pull amplifier, but matching it with high quality pre-amp will be matter of chance. My suggestion would be Perreaux solid state Pre/amp that you can find discounted on the Audio Advisor web-site.
http://www.audioadvisor.com/perreaux/perreaux.asp

You just have to hear Carmina Borana with K-horns and high current amp! Good luck!

Go with a tube pre amp and a solid state amp. Those 15 inch woofers need the control of a solid state amp IMO. I used a conrad johnson pv 10 pre with them and it was no small improvement over a solid state pre,but when I tried a tube power amp, the bass got really loose and sloppy.Look for a used pv10a and a nice little solid state power amp, like a Mccormack dna.5. They really dont need much power,just a few GOOD watts. Happy hunting,
Mike

I have used various amps from 2A3 single ended thru 350 watt solid state. My present amp and favorite is the JJ 828, intigrated with (4) KT88's per channel. I find this gives the sweetness of tubes with good bass control of solid state. I get much better dynamics and control than the smaller tube amps I have tried with my Klipschhorns.

If you like tube-rush noises, microphonics, high maintenance, & an overheated house in warm weather then get some tubes.
I've been through this & the only tube preamp quiet enough was the Golden Tube SEP-2 or SEP-3. Of course I didn't try a whole lot of tube equipment (admittedly prejudiced here) so you might find something else that works if you really try (the Sonic Frontiers Power One didn't cut it for a PA).

Regarding solid state: I've tried more of those amps. Best results were with mosfet output amps, although a McCormack DNA-1 Deluxe did pretty nicely in the bipolar dept. The plain-jane DNA-1 was OK as well, but the Deluxe for a few more $ is much better.
In Mosfet: good results also achieved with Ayre V3 & Perreaux 350. The best yet is Accuphase P-450 which is presently in the system driven by an Accuphase C275 pre.

Belles & Conrad Johnson were both no-go.
Krell KAV250A was OK but the rig wasn't optimized for it, so that wasn't a fair audition (at the time I knew too little about tweaks, cables, etc.).
I tried Classe CA150 as well, but again it wasn't really a fair audition so that could really be good although I didn't know it (the dealer wanted his demo back the very next day so I never heard it actually warmed up, & also repeat the above "not optimized" statement).

Synergy is a critical issue with these speakers & if you're pumping any noise into them they'll absolutely let you know about that. In other words, a clean, quiet signal is imperative due to the highly revealing nature of horns. The synergy issue includes your cabling & tweaks. I've had good results with MIT networked speaker cable. I think that's due to the parallel networks acting as absorbing Zoebel networks across the speakers, which do emit a fair amout of reflected energy back upline / needing somewhere to go beside backing up into the amp.