They are not on the Ascend website yet. For information, give Ascend a call.
As for differences between the CMT-340 and CBM-170, the 340 has better bass extension, is more dynamic, slightly more forward presentation, slightly more efficient, wider horizontal dispurtion, and can play louder without distortion.
Is it worth the difference? For me, yes. But give Ascend a call and discuss your preferences, room size, etc, they will point you in the right direction.
If you are in the LA area, I have both, and you are welcome to come over for a listen.