A6's are similar to an A8, but with a little less treble and output, maybe not quite as clear and clean. A good magnet, but not that different than what's already out there.
A6 is kinda dark, not that many good applications for it. A9 is to A8 what A5 is to A2 -- louder and more bite and grind. Another very viable alternative to succumbing to the evil ceramic empire...