Two stereo inputs into one?

[PoorUB]

I know someone makes this, but simply, I am looking for a device that I can connect two separate preamp outputs into one input. Some sort of combiner, isolator thing-a-ma-gig. 12 volt powered.

[Coyote]

You mean stereo to mono or to another type of single stereo connector?

[PoorUB]

Actually, one mono output, (GPS), one stereo output, (Bluetooth adapter, Bluetooth in, hard wire out) going into one stereo input.

[PoorUB]

https://www.autocom-shop.co.uk/

used to sell some of this stuff.

[PoorUB]

Found it!
The guy looking found and obsolete J&M accessory that will work.