Fuze+ Support for AAC?

I know that the Fuze+ supports AAC files, but does this mean that it will play albums bought on iTunes?  It seems that when I go to put an album on the Fuze+, it converts it to a lower bitrate, is this how it supports it, by converting it?  I thought this meant it would play natively without conversion. 

It natively supports non-DRM’d AAC. Perhaps your files have DRM and that’s why they’re being converted?