Sansui’s late-70’s line of hi-fi equipment is fairly collectible; I’ve had several of them over the years, and they generally sell for good money. My last pair, a tuner and integrated amp, actually went to a prop stylist for a film… I wish I could remember the name of the picture. Anyhow, aside from the usual amps, preamps, tuners, and integrated amps, Sansui also made this very unusual device during the ‘first-wave’ of home-music-production: The AX-7 ‘Audio Mixer.’ A four-input HI-Z mixer, the AX-7 was designed to allow the user more easily use multiple stereo tape decks to ping-pong tracks into a layered production. It also offered global spring reverb!
There is a good-looking example on eBay right now for $99 BIN, which is a great value just for the spring reverb!