In days of yore, when Dolby Surround was the big thing, and Fosgate released a processor, to add the surround channel to your stereo setup.... many simply used car speakers for the surround channel, and the power needed for surround was only 25W RMS....
Surround needn't be as expensive as we Nerds have made it...
Just a single back channel with 2 very basic speakers already gives you 80% of the benefits of surround at very little cost.