Steve told me he intentionally doesn't label the outputs so you try out both and see what sounds better for *your* particular setup. It forces people to think about it, rather than just hooking up to their nominal posts and forgetting about it.

IMHO - if you don't hear much or any difference with your particular speakers, then don't worry about it. Your speakers just happen to fit in that window where one impedance happens to overlap the other a bit, and/or your speakers aren't that sensitive to impedance differences with this particular amp.

You might try listening to some extremes - like symphony with dynamic tympani or something with lots of bells or cymbals. Hit the frequency extremes and maybe you'll find which posts sound better.  :)