I had the VSI-55 and found it had a great 3d picture and great bass authority. I eventually found that I wasn't listening to the cd's in my collection that have great vocals, soloists, or small jazz.
I think it had to do with a slight lack of midrange texture that I find important. I changed the stock tubes and it was better still a little cool. I decided to change it for another amp.
I think it is a very fine amp but it didn't have the mids and the transparency I wanted. Perhaps a mismatch in my system. You can pick up a slightly used vsi-55 for around 2k. I've heard the better ARC reference stuff in a few systems and was very impressed with all aspects.