I use a Carvin 16 channel recording board, and run a power amp after the mixer. I use 5 channels for one guitar, alone, and 7 for keyboards. Regardless, Carvin makes a reasonable inexpensive P.A. brain. You can plug each instrument into each channel, then kick on the one you want to use, and/or cut back the others.(as not to pick up other spurious sounds). Also, if you use a recording board, they are quieter, but require an external amp, after them. The good thing about that set up, is recording is by FAR cleaner, than using the 'record outs' on a P.A. brain! Also, there is a 'Recording Room' output jack, which enables you to use headphones, while playing live(a small ear piece works fine), and it is powered for their use...but not enough to run room speakers. Great luck!. If I can help, in any way, just post a question, I'll answer it to the best I can.
Warmest Regards!
GfS