I did a wee bit of digging and found this - which answers my question in part and thought t may be useful to others with 'issues' especially ipod users as the add on is required.
Fully Supported
Players listed here are equipped to play both unprotected and protected audio files, right out of the box.
iRiver H10 (5GB, 6GB, and 20GB)
Supported
Players listed here work with Xbox 360 but may require a firmware update available from their manufacturer's Web site. The update may or may not allow supported players to play protected as well as unprotected audio files through Xbox 360.
Apple iPod, iPod Mini, iPod Nano, iPod Shuffle (Note: in order to play unprotected AAC files, all iPod players require a free download from Xbox Live Marketplace using Xbox 360: "Optional iPod Support")
Creative Labs Zen Sleek, Portable Media Center, Zen Vision, Jukebox Zen Xtra, Zen Touch, Zen Micro, MuVo NX, MuVo TX - FM, Zen Nano Plus
Dell Pocket DJ
Gateway MP3 Photo Jukebox
iRiver Portable Media Center, IFP-790T, IFP-890T (256MB), U10, T10, H320/340
RCA Lyra RD1072A
Rio Carbon, Forge
Samsung PMC, YP-T5 YEPP (256MB), YP-MT6, YP-T5V/XAA
SanDisk Sansa e140
Sony PSP
Unsupported
Players listed here use a proprietary protocol that is not supported by Xbox 360.
Archos Pocket Video Recorder
Creative Labs Jukebox 2, Jukebox 3, Jukebox Zen, Jukebox Zen NX, Nomad IIC (64MB)
Gateway DMP-X20
iRiver IFP-140, IFP-180T, IFP-195T, IFP-340, IFP-380T, IFP-590T
Rio 800, Cali (256MB), Chiba, Eigen, Fuse, Karma, Nitrus, Riot
Samsung YP-910