I own both Dunlavy Alethas which I believe use the same drivers and crossover as the SC-IV (1 woofer per speaker versus 2 in the SC-IV) but in a more wife friendly enclosure, and Vandersteen 2s. The Vandys used to be my main music speakers but since acquiring the Alethas, the Vandys have been relegated to a basement home theater. Don't get me wrong, the Vandys are excellent speakers but are no match for the accuracy, liveliness and dynamics of the Alethas. That being said, I believe the two do indeed have a similar sound. They both have first order crossovers, phase and time alignment so perhaps that's why. I found the low end of the Vandersteens to be somewhat looser and boomier than the Dunlavys giving some the impression that the Vandys have "better" bass. In my opinion that's a result of the Vandys passive radiator. I've never heard a speaker with a passive radiator that doesn't blur the sound some.
In my room, the response of the Alethas is pretty flat till it starts to roll off at about 35 Hz being about 11 db down at 20 Hz. Just recently I purchased 2 REL Strata III subs to go with the Dunlavys and now the response is pretty much ruler flat to 20Hz. I couldn't be happier and can't say enough good things about the RELs, how we'll they blend with the Alethas etc. but I suppose that's a topic for a different post.
I will second the opinions that the Dunlavys need a big room in order to blend the drivers and offer a massive soundstage. Mine are in a big room, placed on the long wall about 17 ft apart. My listening position is about 15 ft from the midpoint of the speakers. I don't find them particularly difficult to position. They are about 3 ft away from the side walls and about 1 ft from the rear wall. The Vandys however, got real boomy when close to the back wall, again I presume because of the rear facing passive radiator.
I think you'll be real pleased with the transition from Vandys to Dunlavy. Keep us posted.
