The very first ESPRIT unit with which the ESPRIT brand itself was launched in july 1979.

Well... the first one was the APM-9 but it never got out of Sony's R&D departments. Functional prototypes of the APM-8 were shown as early as spring 1978.
Unlike the later APM-6, the APM-8 wasn't that well received in Japan (thanks Munetika!). However, it managed to find its way to the cover of the spring '82 issue of Stereo Sound and garner a State of the Art Award as well !

Myth has it that there were only 16 pairs made but that's myth only. The other 2 ESPRIT APMs (APM-6 and APM-4) sold better, but you don't see these often either - in fact, you never do. Two tests I have at hand show excellent horizontal dispersion and a slightly "polite" frequency response, a staple of Sony loudspeakers.

What isn't a myth is the short lifespan of the drivers' surrounds, mostly the bass driver, and brutal reality is that replacing those surrounds is a very difficult task.

Sony had a dedicated plant to produce its own APM drivers, the latter being as really impressive when they are out of their enclosures as they are discrete whe they are in !

Sony went an entirely different way a few years later with the "bio-cellulose" membranes used in the Voce series, the massive SS-GR1 (1989, another awarded unit) or the small ES SS-G55 and G33 which all used (almost) conventional cones. Not to mention the ultimate and xxx-rare SS-R10 (1995) which was an... electrostatic !

I've never auditioned any of the APM speakers so I do not know if their looks were worth their salt, music-wise - but I sure would like to!