Nope...
The SX1980 failed the FTC preconditioning test of 1 hour of 1/3 power...
Had inadequate heat-sinking and weak power supply, in fact today a couple of aftermarket guys sell a redesigned power supply. In 78, the FTC issued Cease & Desist order to Pioneer after running its own lab tests.
The unit would measure 270Wx2 cold out-of-box but its power output would decrease significantly as the unit got hotter.. When Pioneer was served with the legal action, they abruptly discontinued the SX1980. Back in the late 70s there were multiple monster, high-powered stereo receivers from Technics, Sansui, Kenwood, Pioneer but the only brand marketing high-powered stereo receivers that passed the FTC tests were the Marantz receivers such as their 2385, 2500 and 2600.. Also the Marantz receivers were capable of driving 4 Ohm loads something that the most brands couldn't do. I know a little about this subject as I was the project engineer that did the SX1980 measurements for the FTC...

Just my $0.02...