Tries from Williams, Phillips and a superb team-try finished off by Byrne emphasised the huge gulf in class as the Ospreys ran out comfortable winners.
"I'm looking forward to the challenge of qualifying for what should be a superbteam in 2012, " said Sotherton, who also won heptathlon gold at the 2006 Commonwealth Games.
The Foxes sealed the win when a superbteam move saw the ball break to King, who finished smartly from 12 yards as the Owls slipped into the bottom three.