Power Amp or Mono blocks for JBL K2 S9900

Why in the name of heaven would you want more power with those wonderful and efficient speakers? I would be more concerned with the quality of the amp and moderate power.

@roxy54  - thanks for the input. I went with the measurements on the speakers being 500W capable, hence thought it might benefit from additional power.. Still fairly new to these, so may not be the right query. Anyhow, are there any specific power amps that come to mind which go well with these?

OP, it can
I saw a pair of near new Audio Alchemy DPA monos for sale, I think on USAudiomart for a mere $1500. That should be awesome

I like these JBL speakers--they sound lively, like most horn systems, and do not suffer from excess coloration.  The slight downside is that it is NOT that efficient.  They may not be suited for use with small single-ended triode tube amps, for example, although that would depend on how loud you want to play the system, the size of your room, etc.  

If you can, you should locate dealers or friends that can lend you different types of amps--triode tube amps, pentode/tetrode tube amps, and output transformerless tube amps--to compare with the Krell or any other solid state amp that you can find.  You might be surprised to find that power is NOT the be-all and end-all that a lot of people measure amps.

Nice speakers and amp.
Some people like solid-state amps and others prefer the sound of tubes. You have to figure out which one you like. Personally I like both and I have systems that are solid-state, tube, and a combination of both.
You have a very good amp, a different brand with more or less power will simply be a different flavor of music and the same thinking goes with a tube set up. Since your speakers are 93 db I believe a less powerful wattage tube set up will power your speakers for example a tube set up with 50 watts per channel. When I have a bit more time I'll make some tube amp suggestions.