welcome to the forums.
I'm trying to discover my device in Roku Radio. It finds it OK but says that the MAC is registered to another user; me but an old email address that I no longer have access to.
If you remember the password related to your old account (the one with the email address you no longer have access to) you can try the following to help yourself:
1) Log in to Radio Roku with the old email address and password.
2) In the "Devices" widget (where it says "Discover your SoundBridge devices.") click the name of your SoundBridge.
3) On the next page ("My Devices") click the button "Release" to the right of your SoundBridge's details.
4) Repeat step 4 for all other SoundBridges listed (if applicable).
5) Log out of Radio Roku.
6) Log in to Radio Roku with your new account.
7) Click "Discover" in the "Devices" widget.
If that fails try contacting RokuJamesL by sending him a PM
and ask him to resolve the issue.