Amp suggestions

Horsn are gaenerally very efficient and you can use a low power amp and get very high volume levels. Some folks with horns even use tube amps that put out 10 wpc or less. Would need to know the efficency of the horns. You might run a search for other threads on low power ss amp. Pass Labs 30 is one that comes to mind, but would cost you more than what you want to pay. One v. good ss amp that is only a little more than your budget is McCormack DNA 0.5 which is 100 wpc and would cost you about $6-700.00.

Klipsch lists the sensitivity at 94db. If I went with a tube, how would the bass be? I was looking at one of the Jolida's, I forget which one.

The sensitivity of your speakers would give you less room to play with the volume, but there are many people who use very high powered amps with speakers similar to yours. The nice thing about them is they don't require lots of power, but they can handle it.
You don't need to shy away from the 555 is you want it, but you certainly could use SETs if you wanted. You have lots of options!
Have fun!

First of all I think you are misinformed about to much power. Most speakers are damaged from to little power because the amp is sent into clipping which damages speakers. Keep in mind that you have to double your power that you have now to get any noticeable volume change. More important than the power rating is good clean power and that is especially important with horn loaded speakers. My suggestion for an amp would be a used Aragon even Klipsch likes them they bought the company. My first choice would be used Plinius 8200 but it is about twice the money you want to spend. I don't use any thing but tube amps but I use fully horn loaded speakers and it is a good match. In your case with the new style klipsh I think SS a better match. My feeling is that is that if you want to do it right but conservative save up about 1400.00 and I would go with a good integrated like Plinius 8200I, because to many times amps. And preamps. make a poor interface, with an integrated their made for each other and from my experience that leads to great sound in a reasonable price range.