I remembered it as the 570 which was playing when he was visited. His comment was "They have no right to sound that good", but it may have been the 580s. I'll bet the 580 sounds great; 6.5" is about my favorite bass/mid size for a two way speaker.
You are probably right about that, it's been a few years. I have a pair of Klipsh surrounds with the 6.5 woofer and they do sound better, less boomy, wooly, than the 8 inch two ways in my shop.