Excellent question. If you listen to an SQ-encoded quadraphonic mix in stereo, without a decoder, you will hear a standard stereo mix. SQ encoding is a matrix technology that embeds quadraphonic sound elements into stereo channels. Without an SQ decoder, the quadraphonic elements won’t be properly separated, and they will blend into the stereo signal.
In this case, you’ll hear stereo sound, but the spatial placement of some of the quadraphonic elements might feel a bit vague or imbalanced, as the original intent was to decode the signal into four-channel sound.
