Amplifier for Klipsch Cornwalls

It sounds like what you already have will be more than good enough.

Most high efficiency loudspeakers get their efficiency from tight gaps and precise construction. As a result they are highly reactive and are over-damped with anything more than a very moderate output impedance from the amp.

IOW, a tube amplifier will sound better; will play deeper bass and be smoother and more detailed overall than most transistor amplifiers. This is because a tube amp, especially one with no loop feedback, will not react poorly to the back EMF from the speaker, and will not present such a low impedance to the speaker that it is over-damped (if the speaker is over-damped you can loose as much as 8db of bass in the bottom octave).

I recommend some sort of lower-powered Push-Pull triode amplifier, maybe something with no more than 50 watts. You'll find the speakers doing things you had no idea they could!

a good place to start is a H H Scott, EL 84 based intergrated amp. A nice 222B, or 299B will do a great job with Cornwalls, and shouldn't cost over $500.

Go with SS. Those 15 inch woofers can sound slow and mushy with tubes. A tube pre amp is what you want in my opinion...