Madisound. Look here and call them.
C-151 ... yes, RJA is right, it's Audio-Video Logic in Des Moines, and they should be able to help. Check their web site for more info. I've purchased Martin Logans, Pass Labs, and Audio Research from them in the past, and they've always been good to work with. Buy the Dunlavys if you've got the room for them ... you won't be disappointed. Good luck.
I wouldn't trade my athenas for anything. If the audio world was anything like the rest of the world the value of such a quality product should have sored once the supply was cut off instead of dropping like a rock as was the case with the Dunlavy's.
I don't get the worry over drivers that a lot of folks expres. Outside of clipping an underpowered amp, way overpowering the speakers with a cheap distortion laden amp or physical abuse the drivers should last forever (or at least a good long time). There are plenty of 1950's and early 1960's fender and marshall guitar amps out there that have been pommelled for years and still have original speakers in them.
Don't worry, just buy em.