Amazon Music Unlimited Subscribers can upload MP3 (.mp3) or ACC (.m4a) music files to their Amazon Cloud using the Amazon Music PC App for Windows or Mac. Uploaded Music can be played on Bluesound by selecting Amazon, My Music in the Navigation Drawer.
You can also upload .wma .wav .ogg .flac and .aiff file types as well, provided these files match Amazon's music catalog. Non-MP3 and Non-AAC files that are not matched and cannot be uploaded can be converted to either MP3 (.mp3) or AAC (.m4a). Once converted, these files can be uploaded.
Amazon Music Unlimited will allow you to upload up to 250 songs free with your subscription.