Back in the 1970's, Pioneer among various Japanese brands like Sansui, Sony, Yamaha, and Technics brought popular, budget-conscious audio gear to the masses. With the prices of solid state components dropping, these amplifiers powered many college parties and brought music into the homes of many audiophiles of that generation.
Check out this ad from back in the day featuring the Pioneer SX-780 (45Wpc):
Nice to see that the idea of "high-fidelity" featured prominently rather than some nebulous idea of "high end" audio. Today, let's measure and discuss the sound of the last in the Pioneer SX-800 series of receivers, the Pioneer SX-880 featuring up to 60Wpc into 8Ω. The SX-880 came out in 1978 with a retail price around US$425. Thanks to a large part to central government mismanagement... err... inflation, this would be about US$1700 2020 dollars which would buy a rather advanced multichannel receiver like the Denon AVR-X4500H these days.