This is a device that showed up on Yahoo! Auctions for like 500 yen and kept getting relisted and never purchased. It is a mystery device. There is nearly no information available on it online at all. The main problem is that there are no drivers available...
So what is it? Well it's a serial sound card. Old Macs had limited audio capabilities, notably they didn't have audio input. This card allowed for duplex playback and recording!
I was hoping it would be a licensed or cloned MacRecorder or something so the same drivers would work but I haven't been able to figure that out. They even scratched out the chip markings!!
This is the information I could gather through Google at the time of writing:
If anyone has any more information on this, or better yet has a driver disk! Contact me on Twitter!! @kalleboo
There will be another page for printers