You are forgetting that benefits are not always additive. Sub woofers have long wavelengths, which are not directional to our ears, and hence can be additive. Mid range and tweeter frequencies are not additive....the result will be excessive comb filtering or a vague atmospheric sound that totally lacks focus. Even on a surround system the speakers should all match in timbre and characteristics (means you should really use the same speakers to get the most benefit).
Surround sound only works because the speakers are separated distinctly and the channel information fed to each speaker is specific for that arrangement, including delay adjustments according to specific speaker/listener positions.
Surround sound only works because the speakers are separated distinctly and the channel information fed to each speaker is specific for that arrangement, including delay adjustments according to specific speaker/listener positions.