I think what changes is the distortion spectrum and it can change our perceived spacial perception. I hear the same thing from my 300Bs, you get a perceived wider soundstage.
Our brain is a complex device and how it interprets and processes information is an interesting science. Usually it processes spatial information in terms of delay and direction but there must be some correlation with even order types of distortion that allows our brains to fill-in or deceive us into hearing a larger space.
I don't honestly know enough about the research to do anything but give you an educated guess though.
Nor do I really. But I do have 'faith' in blind listening tests. I suspect more 'proper' research needs to be done in this area. I am rather impressed with Jon Risch's views. Although about cables I think its principles apply generally
http://www.videohifi.com/16_RISCH_ENG.htm'I reported to my supervisor that I had found at least one cable sample that seemed to sound much better than the others, and was even better than the then currently Japanese sourced Gold-Ens. He was also incredulous, and did not quite believe me. So a formal listening test was scheduled to test between the existing cables, and the new sample I preferred, and I was placed under blind conditions (double-blind equivalent). A variation on the original ABX procedure was used, with hand swapping of the cables, instead of a switch box. Much to the amazement of my supervisor and fellow engineers, on the first set of ten trials, I scored 8 out of 10 (still warming up), then 9 out of 10, then 8 out of 10 again. I could tell I was getting fatigued on the last run, and said so. Taken as a whole, the three trials together, for 25 out of 30, approaches near certainty. This was the beginning of my long journey with audio cables, and the why and wherefore. Since 1980, I have been conducting controlled listening tests on audio components, most of which were for audio cables. After literally hundreds of cable listening tests under controlled conditions, I have no doubt personally that cables can be detected and some sound better than others. I know this, and no one can take this away from me, there were too many tests with overwhelming positives, too much rigorous science involved. After conducting many tests, and finding out early on that they were not always so easy to get results from, I found that there were weak spots in the original ABX procedures, and with many of the amateur DBT's that had been, and were being run (mostly by cable naysayers). I wrote and presented an AES paper in 1991, AES preprint #3178, outlining some of the issues connected with listening tests, and based on my own experiences with having conducted so many listening tests.'
Thanks
Bill
