As mentioned in my project thread, I need to convert from stereo to mono, so I can run just one speaker in the factory location.
I found a simple wiring diagram (see below) that apparently can convert stereo into mono, however I have found that it distorts the sound and also really limits the volume. Can any of the electronics experts here tell me another way to get around this?
If I read the schematic correctly, I put resistors on all 4 wires (R+, R-, L+, L-) and then 1 big one between them. I have used std type resistors rated at 1W.
Schematic:

My wiring:

