I have a new Sony Bravia DAV-HDX576WF. When watching DVDs or HDTV with 5.1 audio, the rear speakers are working, but you have to stand right next to them to hear them. I can't figure out any way to make them play louder. Any thoughts?
You may not need to! The important thing with surround speakers is an effect of sound behind you, it shouldn't be too loud or noticable.
However if you have not done the auto calibration yet:
(from Sony Style)
Simply place the included microphone in your listening position and allow the strength of Sony's Digital Signal Processing to take over. Speaker placement, distance, and delays are all adjusted automatically to ensure a worry free listening experience.
The instructions for doing this is on page 90 of your manual or hereby clicking "operating instructions":