When introduced for the 1973 model year, the Lafayette LR-4000 had the industry's one and only "full logic, wave-matching" SQ decoder, and as such, offered the best SQ performance available at the time. The unit was also a pretty decent receiver in terms of power and FM performance too, producing about 40 watts of real power into each of the four channels (a lot for the time).
Subsequent Lafayette receivers had improved SQ circuitry, including a feature called "Vari-blend," which all but eliminated the front/back "pumping and breathing" common to the standard full logic, wave matching circuitry.
At $30 you really lucked out. I"m sure you could sell the unit for considerably more than that if you choose to.
