Yesterday I noticed a Sansui QRX-9001 in a local thrift store (too bad I forgot take photos). Basically it's a surround receiver (surround processor and power amplifier in one box) that upmix stereo signal into quadraphonic signal --either plain stereo or using particular matrix format like SQ and QS, but it also accept discrete quadraphonic format like CD-4 vinyl. So, it is not unlike your modern home theater receiver, which typically supports modern surround formats like Dolby ProLogic (matrix) and Dolby Digital (discrete), but it came in mid-1970's, with now-dead format like QS (matrix) and CD-4 (discrete).

More than two decades later, early PC surround sound cards come with 4 channel. Typical Aureal 3D cards are quadraphonics --models like Turtle Beach Montego Quadzilla, which requires add-on card for quadraphonic, and Diamond MX300, which doesn't. At that time, I also had an Altec Lansing PC multimedia speaker set that accepts 4.0 input but emits 4.1 output; four satellites and a 'subwoofer', that is. I was avoiding Creative PCI sound cards like a plague at that time, but it seems early Live! sound cards were also 4.0. Yes, multimedia speakers were actually 4.1 instead of 4.0, but they generally had 4.0 inputs, so I guess 4.0 (quadraphonic) was really the thing at that time.

Too bad these two never met. 🙁

They're made for each other, really.

I wasn't really into audio at that time, let alone vintage audio. Because if I were, I would definitely buy one. Since a quad receiver like Sansui Sansui QRX series can accept both plain stereo and discrete quadraphonic channel, then it would be perfect for a typical DOS/Windows 9x dual boot PC of the era; the plain stereo input is for ISA sound cards like Sound Blaster AWE64 gold, while the discrete quadraphonic input is for quadraphonic sound cards like Diamond Monster 3D. Of course, unlike typical PC multimedia speakers at that time, a quad receiver cannot convert 4.0 to 4.1, so you cannot have a "subwoofer". But you typically use quad receiver with full-sized speakers anyway --something like JBL 4311 or Klipsch Heresy, so who needs "subwoofer" anyway? And wouldn't it be nice to have such fitting receiver for your typical DOS/Windows 9x dual boot PC?

Nonetheless, those two things never met. Mid-1970's surround formats were short-lived, replaced by 5.1, 6.1, and 7.1 brought by Dolby and DTS. Quad receivers have been long-dead when quadraphonic sound cards came out. I still think it could be interesting if quad sound cards and quad receivers met each other, though.