It's really interesting to see how all of us agree "in principle", yet we are in separate camps, in many ways, on "practice".In theory, theory and practice are the same. In practice, they are not. - attributed to Albert Einstein, Yogi Berra!!!! and Jan L. A. van de Snepscheut.
One of the problems here is we have no universally accepted way of "measuring" or judging if we have achieved our objective, i.e., better sound. We can't even agree on what better sound is. That's OK. Better sound is, despite our best engineering and scientific efforts, a judgment call. Beauty is in the ear of the beholder. That's not to say that Doug's observations are incorrect (I think that they make a great deal of sense and explain very well why different people report different results) or that there are not certain principles, theories and practices that we can agree on. But when it comes down to whether or not a ring clamp is "better" on a particular TT/arm/Cart/RIAA/pre/amp/speaker system than a center clamp or a center clamp + ring, ultimately, you have to decide yourself whether the practice (what you hear) conforms to your theory. If not, then maybe your theory needs to be revised... or maybe your practice. No way for us to know in advance. I also think that part of the problem is our innate desire to oversimplify complex systems.