How to connect my Cell Phone to my DAC?!?!

Hello,

i have been told it is possible to connect my cell phone directly to my DAC and play music from the phone, but can't figure it out.  :(  DAC is showing "44Khz" message so it KNOWS that something is connected to it, but it never plays any music.  I am using an "Audio USB" cable from a DJ supply company.  The same phone and same cable work fine going into my Hegel Amp (internal DAC) but no sound comes through when trying to use EXTERNAL DAC.  The item in question is the SMSL SU9n.  I cant find any email contact at SMSL.  i wonder if anyone here would know how to troubleshoot this problem.  Thank you for your comments.