So the documentation and the early reviews say that the E09K only works with the E17. The later reviews I see say that the most recently produced E09K will work with the E7 although all the reviewers are using the E17. It sounds like Fiio may have fixed whatever issue prevented the E7 from originally working so I wanted to see if anyone has used them together successfully.
I currently have an E7 and looking to buy an E9. I would consider the original E9 but I would like to stay with a current model if it will work.