routing more than 2 speakers

[sugarplumsss]

Where can I find as much detail about sending signal to 2 speakers as well as three an four speakers? Stereo on stage is important. The midi songs sound best in stereo as well... and a higher than average volume gig, requires more than 2 speakers.
Where is this info found?
I am using a Bose L1 model 2 with B2 sub plus 2 k10 speakers, and a fourth speaker.