Sound cuts out when connecting to Google Satnav

[Raystr]

Hi everyone, I have a small but VERY annoying issue...am I doinfg something wrong? When I attach my phone (via cable) then use Google to plan a route, it appers to cut the audio from my USB stick which contains my music files. This doesn't happen when using MG's (CRAP) satnav. Is there a setting that will allow my music to keep playing and still use the Google Map satnav.....Thank you so much for any help!