Yes, the standard prescription is to wire one speaker out of phase. Leaving that out was an oversight on my part. Even with the Gallos this should offer some spl reduction, as most basements and most ears would be concerned more with the sound in, I don't know, the range of male vocals (maybe up to counter tenor), roughly. Low bass and high, directional frequencies really wouldn't get out of most braced basements so easily, and ears tend to be less sensitive here anyway.
