As Alabalcho says you want more than a soundbar is designed to do.
I would suggest you either use your old receiver just for the outdoor speakers or if the budget allows get a Sonos ConnectAmp or Heos Amp to drive them. You will be able to control them with phone or tablet and stream music or play files to them.
You can add a Sonos Connect or Heos Link to your receiver and save a few bucks.