OK. I don't recall reading that thread before. The author
emaidel used to sell Lafayette and so might be a bit biased, then again he puts down a lot of what Lafayette was selling back then. Sadly he hasn't posted since 2015, his posts are rather interesting! Anyway I have no doubt that the Composer produced a nice surround effect but to say that it was better than Sansui is very unlikely.
The early Sansui decoders were nothing special even with thier "phase modulation" circuitry however Vario Matrix is a whole different story!
So checking the schematic of the SQ-W the decoder functions are as follows;
Position 1 (Stereo) the input feeds through to the front and rear outputs, the rear outputs are reduced in level by about 7db.
Position 2 (Composer A) the input feeds the front (the same a pos 1), the rear outputs come off of a differential amplifier and feed the rear outputs. So it's an active version of Dynaquad.
Position 3 (Composer B) The outputs come out of the SQ logic circuit with the logic turned off. So it is just the "basic" version of SQ.
Position 4 (SQ) The outputs come from the logic circuit with the logic turned on the rear outputs attenuated a bit via a 47K resistor.
Position 5 (Discrete) The 4ch inputs pass through to the outputs attenuated by level matching resistors.
So no actual RM decoder is used and no form of logic enhancement but for full logic SQ.
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I ran a lot of stuff through that RM, especially non quadrophonic albums from a CD player and records sound very much like they were made in quadraphonic going through it too! I'm curious what happens when you play regular stereo through the QS from a Sansui Is there any kind of magic like when I run regular stereo through RM on the Lafayette?
