If you use something like a POD as a preamp, you should use an accurate, 'stereo quality' power amp - probably a brute of a transistor job. PODs (and suchlike) simulate the sound of a tube power stage, so you want to feed that signal through a power amp that will accurately reproduce the sound, and then feed that to a set of speakers that will also reproduce accurately.

Tube amps do strange things to the signal they receive from a guitar, which is not the same thing as just making it louder.

If you use a simple preamp that doesn't add any amp simulation, then you should probably use a tube power amp, and guitar amp speakers. If you use a preamp that has amp modeling capabilities, then you want to be able to deliver that sound to your audience as cleanly and accurately as possible. That usually means a PA type transistor amp, and full-range speakers.