Sony STR-DE545 receiver

Heres the link-
STR DE545 SONY FM STEREO FM AM RECEIVER Manual

Go into the settings and select Demo Mode OFF

From page 46 (Troubleshooting)-

No sound or only a very low-level sound is heard from the rear speakers.

>>> Make sure the sound field function is on (press SOUND FIELD - MODE).

>>> Select a sound field containing the word "cinema" or "virtual" (see pages 28-30).

>>> Adjust the speaker volume (see page 19).

>>> Make sure the rear speaker size parameter is set to either SMALL or LARGE (see page 17).

Yes, you can hook it to AUX, it is really doesn't make much difference if you hook it to CD in or TAPE in or AUX, just press corresponding button in the front :)

It only works through DVD setting

Yes I do! I hade the same problem so went to radio shack and got tow Y -RCA splitters with one male and tow female works great!!

Make sure the subwoofer is set to On in the setup menu. Should be able to access this setting from the front panel, using the click wheel and the left/right buttons above the wheel. Push the setup button to get to the right menu. Set subwoofer to 'on' and speaker size to 'small'. This receiver has a fixed crossover, so make sure to turn the crossover setting on the subwoofer to the maximum setting (highest frequency) to ensure no signal is lost.

Find the user manual under product details.

I just turned my DVD player off when my STR-DE545 was still in DVD input mode and it came up LOCKED, maybe the input that you are using is not receiving a signal?

Are you connecting from your DVD player to receiver using an optical cable or simple AV cable?