I found that I can wiggle the jack in the speaker bit socket, with it about halfway out, and get a strong audio signal. If I put the plug all the way in, I get a very quiet signal output, or no signal. I did not have any better result with a mono cable. However, your results may be different.
Above all, I recommend the USB audio output bit for connection to a computer, iPad, or iPhone as a much better option than the Speaker bit.