13. Can I upgrade my BTR1 version 1 to support AAC?

A: We're sorry that the BTR1 does not support firmware upgrade on the user's side. If you want to upgrade BTR1, please contact us by email(support@fiio.net) and send the BTR1 to us. 

BTW, the BTR1 version 2.0 supports the AAC codec. And there is a label "ver 2.0, supports aptX, AAC, SBC" attached on the packaging box for the version 2.0.