Hi Gopher, actually one of the big selling points of the Def2s when I bought them in 2007 was their coherence at low levels. This I believe is a big function of the high sensitivity and lack of crossover so less energy sucked out of the presentation.
In a major way this was a pivotal reason to buy them, to be able to enjoy my music more intimately between 10pm and midnight.
It's a shame if you haven't had this in your experience.
Phil, can you inform us about low level listening, thank you.