I could use small headphones from the keyboard jack, but wonder about actual speaker volume if I am hearing headphone volume only. Having the Bose along side would still not allow me to hear the balances of L&RH and bass mix accurately with full extensions. For that matter, headphones would be good, but would not reflect the speaker difference if any.
I do have a pair of CM30's, and could try one, although I am not so vain as to avoid small headphones either. Maybe if I keep the phones at a low level, I could still judge speaker volume. I will have to experiment.

At the tail end of the banquet, I took off one extension and slipped it under the base of the Bose. This allowed me to hear, but not sure if it reached 100 ft or so back with 200 people. I have some ideas to try anyway. Thanks.