Russell the fast8 is one of Lii’s mid tier quality drivers. The fast 10 series is part of their top tier along with crystal 10. They share fast in the name so it’s confusing. That’s why the big price jump
It would seem that is what Lii would have up believe—that more expensive is necessarily better—but I am a sceptic at heart and like evidence of some sort.
I certainly would like to know (from the manufacturer) the specifics of the differences between the Fast 8 and Fast 10B, also the differences between the Fast 10 and the Fast 10B, not to speak of the Crystal 10. I have to say the crystal on the pole piece really puts me off. Is this acoustically meaningful or a tacky attempt to appeal to the nouveau riche crowd who are interested in buying 'up-market' bling?
I presume cone material and magnet size and/or quality is one variable, and I hope this translates into better sound, but it seems hard data is in short supply. I read somewhere that they use—at least on the Crystal 10—a higher than usual grade of ceramic magnet, but maybe that varies model to model. It would be nice to see real response curves with THD levels at three or more different output levels.