Can I use a guitar amp head as a power amp?

Power amps can get a bit pricey… is it possible for me to use a powerful guitar amp head as a power amp? If I plug in the components (guitar, bass, microphones) into a mixer, then plug the mixer into the amp, then run the amp into a speaker, will that work?
Also, if this configuration is possible, would it also be possible to make it stereo?
Thanks!

Tagged as: Amp Power, Guitar Amp, Guitar Bass, Microphones, Mixer, Power Amp, Power Amps