Have you looked at the site Clarisonus? It is a web magazine that has as it's members Earl Geddes/John Atwood and many other prominent designers and consultants. They have a current discussion ongoing about loudspeaker design with all those I mentioned and more. It is very interesting. One of the reasons I mention Spencer Hughes is because the BBC had and has the most current and thorough laboratories for measuring sound available. One of the reasons they consistently are quoted in regards to audio. They are also one of the only serious design groups with access to the BBC Orchestra. They design around pink noise to start; then step outside the booth and listen to it played back by a live orchestra. I think that is why they do classical music better than anyone else in loudspeakers. They were also the first organisation to employ laser interferometers to study driver behaviour.