Just a couple of comments. Not using a sound system is the ultimate desire I think, but only if the natural acoustics of the room are good. Many coffee houses over here are in church basements with low ceilings with acoustic tile. Put twenty people in the room, and they soak up much of the music. I ran a concert series without sound for 27 years in a room that was acoustic heaven. Even with 120 people in the room, you could hear a mountain dulcimer clearly in every seat in the room. But, it was designed as a music room with a cathedral ceiling, so it was a perfect place to play. When things are less than perfect and especially when I'm singing with my gospel quartet, an amplifier and four mikes are essential. Voices are instruments, too, and need to be balanced.

Jerry