I would love to know the answer. My Sonic Port VX was working great until I updated to iOS9, since then I get no sound at all. Line 6 keeps telling me iOS 9 is supported but I get nothing going through Mobil POD and Garageband.
Since it's still under warranty I think I'll just exchange it at the retailer for a brand new one, then sell the unopened box on ebay or Craigslist. I can't use equipment that simply won't work. Maybe someone else will have better success with the new one - I'm pretty much done with this.