@hifineubee you're saying the D4 series has that much better bass response over the D3 series? Driver and cabinet wise, they appear pretty much identical. I'm not sure how they squeezed that much more bass out of them but kudos..
It was said above the the older 800 series were "warm and full"... I can definitely agree, however, there is a midrange crispiness that I feel is warm YET resolving at the same time. I heard the 801 D2 and they were nice but wasn't overly impressed. My older 801 s2's made me smile though when I hooked them up. Just makes me want to listen.. I had the same experience with my Duntech Crown Princes and Martin Logan 13a's.. Just ahh nice