Now we have supported Amazon HD and Ultra HD from both the WiiM Home app and the native Amazon Music App. The Amazon HD is lossless audio in 16-bit, 44.1 kHz and Ultra HD is in 24-bit, from 44.1 kHz up to 192 kHz. You can have the bit perfect output from the optical port with the fixed volume option set. Please find more details here.
Check our release notes for more updates.