Thanks for that Glenn, very interesting and informative and though messed around with sound and amplification in a small way in the past, it is the first I have heard of this technique. Very odd that it isn't very popular or well known as the advantages are clear to see once the principle is understood. Considering that Alan Blumlein patented it in 1933 and used it around that time, why is it not more well known? To be able to change the stereo mix, spread it or narrow it down via the original use of this system is amazing.