Years back, Lexicon during the Dolby Pro-Logic age made a processor(could have been the CP-1,CP-2 or CP-3) that had side speakers. I was able to get a demo of this in a store that had a set-up very close to the DTS set-up shown above. The side surrounds on this processor sounded nothing short of fabulous.

I know that even in movie theaters way back in the early 60s there were speakers along the sides and most definetely in the THX theaters of the later 1980s. I remember seeing THE LIVING DAYLIGHTS in one of those THX theaters. There was a scene where a cable car on its tracks passes you buy and you could hear it go from side speaker to side speaker down the theater rows. It was a feeling of side sound nirvana. Not long after that I perfected a five channel Dynaquad system and played the same scene from a laserdisc. The rear surround speakers of this circuit which faced me like the side surrounds pictured in the above diagram. I did hear the same effect but it was only a one speaker effect which did not compare to the movie theater affect with its multiple speakers. A set-up like the DTS diagram would IMHO reproduce something close to the THX theater's results.