Fred, for what you describe I would try a pair of small diaphram condensors. The Oktava MC-012 are widely recommended, and provide the option of buying the additional capsules fo an exceptional value. If you're looking to capture the room sound, I would place them in an X/Y arrangement, with the center oriented in the place where the band sounds best. You, or a helper, might discover where this is by walking around the room with one ear covered while the group plays.
As for mic pres, I would bet that your Spirit board pres are adequate. I would take the signal directly out of each, rather than from the main outs in order to bypass the additional noisy circuitry. If you simply must purchase something, be warned that to significantly upgrade mic pres can be very expensive. I'd advise you to avoid those which add "color" in favor of the cleaner pres. Perhaps, the DMP3 would suit you. Or, if you can wait, the RNMP from FMR is expected anytime before the apocalypse. That's what I'm waiting for.
-kent