The Perfect Solution When Rear Speakers are Not an Option. For everyone who cannot or chooses not to use rear channel speakers but wants all the thrills of five-channel surround sound Definitive Technology offers the Solo Surround Array Series loudspeakers. The SSA models incorporate Spatial Array a unique patented technology that optimizes the spatial presentation of five channels to create the illusion that you are surrounded by five separate high performance speakers. Enjoying a superb sounding audiophile-grade surround experience has never been more convenient. Simply connect an SSA to any multi-channel receiver and powered subwoofer to enjoy enveloping surround sound without the bother of running long wires and finding places for rear speakers.