I'm sure it depends on the intended use. This would be for jazz combo gigs at relatively low volume in small venues, where the keyboard and bass tend to be either acoustic or self-amplified, and a PA is only for reinforcing a singer or horn player. I've got the pieces to assemble a simple PA with one lightweight speaker. My question is: Is it vital to have two speakers? What would be the harm of having just one speaker on the bandstand? Of course I'm tempted to try it regardless of anyone's advice. But I always welcome both technical and practical knowledge, and I know that there are TB'ers with much more expertise on sound reinforcement than I have.