I have been using an RM200 in conjunction with Wilson WP7s for quite some time and have heard this combination with three different preamps in my own system, and a couple of other preamps in a few other systems.
The first few combinations I heard were in a dealer showroom where I heard the RM200 and WP7s with a Hovland HP100 and a Jadis JPL. The JPL was more more tonally rich but seemed to slow the tempo of music down. The Hovland was more extended at the frequency extremes but images seemed to have less body. Nevertheless, I preferred the music when the Hovland was in the system.
After obtaining a RM200 and WP7s for myself I auditioned a few preamps at home. I had a Spectral DMC10 delta that made the music sound very precise and pure but left me unengaged because it was kind of colorless tonally. I listened to the HP100 again in this system, which I liked a lot more but seemed to present the music as if it was occurring on the other side of a window. It was a bit remote and left me a little disinterested. Finally, I listened to a Wright Sound Laboratory WPL20, which was really inexpensive but highly recommended by a friend. I liked this most of all because it had the extended frequency response of the Hovland but it also let the music flow outward toward me in much the same way it does during a live event. There seemed to be less in the way. I kept it and I am still using it.
A friend of mine has nearly the same system that I have but he uses the HP100 instead. It sounds very good but always seems to leave the music a little distant no matter how loud the system is played. He prefers the Hovland to the Wright which he thinks is a bit less refined and too brash for his taste. I have also heard his system with the latest iteration of the Audible Illusions Modulus 3, which is also very nice but seems to miniaturize everything to the point that it seems like everybody is playing in a box.
Hope this is helpful.
