The supplied Sharp isn't going to work. You can buy a cheap universal to control both. Some of the Sony functions will need to be manually programmed into the remote, but it can be done. You need a UEI manufactured remote to do this. Here's two fairly new designs that will control both the TV (setup code TV 0818) and the Sony (setup code Audio 1658):
OneForAll URC8820/10820 (Sears and internet)
RCA RCRP05B (Walgreens, Best Buy, internet)
Both are $20 or less.

DAV-S500 functions such as volume (but be sure to setup volume punchthrough; otherwise the vol commands may go to the TV), power, arrow keys will work out of the box. Others need to have a 5 digit EFC assigned to button. See posts 2 and 15 in this thread to see the available functions. If you decide to go this route, post back and I'll write up a more cohesive post on how to program all the functions.