We use couveture from Marou.
Marou is a Vietnam based chocolate company that specializes in bean-to-bar production. They are ethical, their supply chain is transparent - I mean, crystal clear - and their product is superb.
Read about them here:
http://marouchocolate.com/post/55952141446/press
Check out their stuff here:
http://marouchocolate.com/post/58397164815/products
We use their Vietnam Couveture 65%.