Tube Preamp with Solid State Amp?

That's exactly how I set up my system and I like it. I was doing so much streaming that I thought a tube preamp would add the right dimension and it has. I read about the Prima Luna Dialogue for a few years and finally added it to a pair of SS amps. The result is great. Only drawback is you can leave the SS amps on all the time but you have to switch them off when you turn on the tube preamp but that's the only drawback I've experienced over the years.

I run a deHavilland Ultraverve tubed preamplifier, modified with Dueland caps into a big Bryston 14bsst amplifier. Very nice results!

As you have Klipsch, I'd recommend keep your P5 and try swapping out your A21 with a tube amp.  I tried tube pre/ss amp a long time ago (Audible Illusions+Exposure) and really liked it, but practical considerations in integrating HT with my stereo setup kept me with SS pre/pro.  I recently moved to Rogue amplification, and have never looked back.  Audition a tube amp and see how you like the sound.

Tonight I hooked up my ss Jeff Rowland to match up with my CAT SL1 5000 series. The tube preamp is always, at least in my systems, the heart of the system. When I want a little sweeter sound and with slightly more depth, then I utilize my tube mono blocks, when I want instant on and a very precise overall musicality, then the ss amp is there. Different flavors, BUT the tube preamp is always at the heart. IME, a ss preamp just isn't going to give you the same musicality and palpability. Same thing goes for a ss phono preamp vs a tube phono preamp. Which is why I use a tube phono preamp ( part of the CAT). 

Don Sachs II (Jupiter cap 2.2uF) with Accuphase P-6100 powering Audiopax Mandolin II ceramik. Beautifull and dinamics. From Brasil.