QUOTE(rosfrog @ Jul 2 2008, 11:10 PM)
If you ask a dealer, though, you'll find that sound quality doesn't come into the valuation - it's other factors, antecedent, condition, how much is left remaining of the original instrument etc. The sound of an instrument is rarely, if ever, used as a factor in its valuation (at least according to J.A. Beare)
For dealers, sound quality (whatever that means) doesn't come into the equation at any point in the food chain from Gliga to Stradivari. The best sounding Strads, though, do tend to have the best antecedence. Having said that, the last time I heard Paganini's "Cannone" (OK, it's a Del Gesu, but you get the point) it sounded distinctly average!
Let's not forget that the instruments of Stradivari, and those of the Amati and Guarneri families are stunning and innovative works of art created by geniuses. That is why they cost what they do.