Napster songs will not play thru USB. Tried on my Creative Zen X-FI, brings up the name but skips the tracks. At least so far I have not been able to get them to play.
My solution is put MP3 player in back cup holder and use AUX Line in. Works ok for me.
Regular CD's songs copied to my Zen work fine.
2013 2SS, GM Strut Tower Brace, CAI Intake Black, VMAX TB, Elite Catch Can, Hotchkis Chassis Brace, Hurst Shifter, 3.91 1LE Complete Rear End, NPP, 1LE Track Pack,Factory Reproductions Style 41 ZL1 Fitment Wheels 10" on all 4 corners