I am the friend to whom Raquel referred. I ran the Dunlavy SC-Vs in my system for three years, and, as Raquel mentioned, I auditioned the SC-Vs alongside the SC-IVa's at a dealer prior to buying the SC-Vs. I wanted to like the SC-IVa's due to their more manageable size. However, I found that, to my ears, the SC-Vs were better by a fairly large margin. The most notable difference was that the midrange in the SC-Vs had more presence. By comparison, the SC-IVa's sounded as if the midrange instruments (horns and the like) were playing from a backstage location. If you have the room for the big dogs, I suspect you will prefer their sound. FYI, I ran my SC-Vs in a medium-sized room (roughly 15 x 20 x 8).
