Here's an Audio World ad from the January, 1973 issue of National Lampoon.
The two-page ad is badly scanned (blame the PDF copy of the magazine on the DVD collection I own) - but it says "five great reproduction systems...". Numbers one through four are stereos, and number five is a naked woman.
Since National Lampoon was never shy about showing naked women in their magazine, I guess Audio World figured they'd get into the spirit of things.
This is the type of ad that would never fly today. Audio World would have the National Organization for Women on their asses, and National Lampoon would probably have to cease operation.
Sexy ads like this were positively de rigueur in 1973 - especially aimed at the free love crowd.
You can click for a bigger view. But yes, I did pixelate the naughty bit.
