Sanyo ASX-3500 - What are 9 pin DIN cables still good for?

[SourCherry]

So as I was going through my basement the other day I found a surround sound system laying about. It consists of a powered subwoofer with 5 other smaller speakers for the surround sound configuration. The subwoofer has an audio input that uses a 9 pin DIN cable but I'm not sure what I can even use this for. Looking at the manual that I found with it, it came with a vhs player that also used a 9 pin DIN cable for audio output. So my question is what can make use of these speakers, or what even uses 9 pin DIN cables still? We have an extra room in my house now that I'd love to turn into a den area, and having surround sound in it would be pretty cool. Any feedback appreciated as always

 

[hang-the-9]

That is likely a custom wired connector for the speaker, not one you can just swap out for any other connector that looks like it will fit.