I would definiteley consider upgrading the interface of your mobile device from a headphone jack -
 
While not really providing the best fidelity - in my experience it can very easily fail in a live setting.  When unplugged, even halfway would jeapordize the flow of your performance.  Also - you'll get better audio, Stereo field (if the live pa can accomodate) and you'll be able to perform with more of a feeling of security.