Avalon Ascent IIs vs. Vandersteen Model 5s

I have a pair of Avalon Ascent IIs. I like their soundsstaging and imaging, focus, tonality, transparency, and really just about everything else they do. The problem is that I cannot get below 40 hz in bass out of them. I am trying a REL Stadium III sub-bass with them and although it has added great foundation and bass, it seems to muddy the midrange and highs. To be fair to the REL, it is probably crossed over too high (at about 36 hz; I've heard them do better at about 25-26hz).

Anyway, I was thinking of trading them in on a used pair of Vadersteen Model 5s, which have great bass and most of the characteristics I like about the Avalons, although, I don't like those characteristics quite as well in the Vandersteens. Of course, I have heard the Avalons in my room, and I have only heard the Vandersteens in a dealer show room. Since there are no dealers close by, I won't be able to hear the Vandersteens at home.

Does anyone out there have experience with both of these speakers?

Also, the reviews say that the bass in the Vandersteens require professional set up to get the bass right. Has anyone bought them used and successfully set up the bass without professsional help?