Having worked for Lafayette Radio from 1962 through 1976, I am quite familiar with the LR-4000 and the LR-5000. The LR-4000 was the industry's first (and only) quad receiver to incorporate full wavematching logic SQ circuitry (dubbed "SQ-W") and was a fairly decent receiver on its own. The ludicrous power rating of 360 watts was no more ludicrous than the power ratings of other products of the day. Eventually, the industry policed itself and stopped the ever ridiculous manner in which receivers suddenly jumped overnight from a rating of 175 watts, for example, to 225 watts for the identical unit! The actual power per channel (utilizing today's standards) was probably about 35 watts per channel. It also had a proprietary circuit called "Composer A" to simulate a 4-channel effect from standard stereo sources, and this circuit, entirely by accident, also turned out to be tested as the best available for the Sansui system (confusingly labled "QS"." The retail price for the LR-4000 was $499.95.
The "new and improved" LR-5000 was a slightly more powerful receiver, with a further improved SQ circuit (employing a never-explained process called "Vari-Blend"), and in keeping with the tradition throughout the industry, eschewed the outstanding "Composer A" circuit for a standard QS, or as it was now called, "Regular Matrix" or "RM" circuit instead. Playing regular stereo source material (2-channel) through the RM circuit yielded a decidedly lackluster effect as compared to what used to be achieved through the "Composer A" circuit. The price of the LR-5000 was $569.95.
Lafayette also manufactured the industry's best outboard SQ decoder for a retail price of $99.95. It had an even better SQ circuit than that which was in the LR-5000, and also incorporated the wonderful "Composer A" circuitry. Adding this outboard device to an LR-5000 resulted in a vastly superior product to the older LR-4000, and once again provided listeners with remarkable effects from standard 2-channel sources.