Stereo to Mono Summing Adapter

You need a mono summing adapter. While not perfect, they're easy enough to build with a few inexpensive parts.
 If you don't use the summing adapter the separation of any of the stereo you might be using elsewhere will be severely degraded.
Instead of the stereo miniplug on the left you'd have the two separate
RCA cables, each one feeding one of the resistors and the shields tied common.
The resistors shown are 4.75k (1%) on the left and 200k (1%) on the right. Why not wye?

It is preferable to build this into a metal project box.
1/4" stereo phone plug one end and xlr female the other.
use headphone to stereo mini to get the signal in from 3.5 mm headphones.
From Ipod
Matching Box with transformer.



3.5mm to dual 1/4" phone ~$8.95

3.5mm to 1/4 adapter


Link
 Link To Buy
Passive Box
Y cable  > Console or crossover.


Cable to xlr.




How to.
Video







CA cables, each one feeding one of the resistors and the shields tied common.
The resistors shown are 4.75k (1%) on the left and 200k (1%) on the right.



Bluetooth in.