Actually, there were some CD's issued in matrixed surround formats, such as Dolby Surround. There were only two channels recorded on the CD, but playback through a Dolby II receiver produces 4.0 surround (not as good, of course, as multichannel SACD's or DVD-A's, though). Some of these were issued by Delos, others by RCA, and I've seen some very low-priced classical "hits" CD's in the bargain bins at BestBuy that were Dolby-encoded. Telarc also issued a Wendy Carlos Switched-On Bach 2000 CD that was Dolby'd, as well as various "Spatializer" recordings that contained matrixed ambience information for the surround speakers.