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

DAC works with Bluetooth and with Optical  but does not work with USB input.

Same behavior when connected to 2 different Amps.

Phone works with Hegel and with USB, just to show that the USB cable is not at fault, and MAYBE the phone is not at fault.

So the SMSL DAC does not make use of the USB input at all, but it does recognize that there is something plugged in.  (768KHz note lights up).  There is either a SETTING somewhere that is making the DAC incompatible with the phone or the DAC is totally defective when it comes to using the USB input.    :(

Good luck getting support from Shenzhen. If you bought from Apos the support is OK.

Any S.M.S.L DAC I've ever tried had no problems with USB in, including the 9n.

Try unplugging the dac and rebooting it,  sometimes that helps.

Not trying to be a smart ass here but when you hit play on your phone Spotify app, does it actually play anything and if it does did you try raising the volume on your phone? Sometimes the volume defaults to zero. 
Also check Spotify settings make sure you’re outputting either mp3 or redbook (16/44). 

@audphile1 you are probably closest to the truth !

This morning, tried to play Spotify on JUST the phone speakers and the volume WAS set on zero.  Even after i manually turned it up, would not even play on the cell phone speakers.  After re-starting the phone, it WOULD play on the phone speakers.

So, now, i am thinking it is not the DAC at all.  Something between my phone and Spotify...   Android Motorola $85 special, lol.