Mixer/One Speaker Question?
 

For my mobile setup I have the Yamaha MG06X. I'm running it to one Bose S1, playing backing tracks off my phone. The problem is the mixer doesn't have any balance control to pan left for mono.
My question is: Running one XLR cable from Left out into the speaker the way to go? or

Went to guitar center and they said I needed a XLR male to dual XLR female splitter

I have the MG06X and I usually go dual XLR out to dual RCA into my L1C. Now that I sold my L1C, I'll probably just run it mono into a single powered speaker (left XLR out to XLR in). Be sure the mono/stereo button on the mixer is in the "mono" position.
Another possibility is to go out the headphone jack of the MG06X with a 1/4" TRS into the AUX in on the Bose with 1/8" TRS. Make sure it's a good quality cable. That might be a cleaner setup rather than having lots of thick XLR cables and y- cable everywhere.

Also, I've gone this route to a Kustom PA50: dual 1/4" TS from the MG06X (unbalanced) out to 1/8" TRS to the AUX in on the speaker.

There should be a "mono" button, that should be in the UP position. Then use only the left side output to your speaker.
~Bob