 Unlike the earlier Full Wave-matching Logic decoders for SQ, that varied the output levels to enhance directionality, the Tate DES cancelled SQ signal crosstalk as a function of the predominant directionality, keeping non-dominant sounds and reverberation in their proper spatial locations at their correct level.The 101A was later replaced with the 3601.The Fosgates were audiophile units of rather high expense and limited availability.