I'm going to give you an "idiots" guide:
0. make sure the copper wire has been exposed on the ends of the speaker wires (YES! I've had somebody expect to conduct electricity through a plastic sheath before !)
1. Check speakers to see if they work. Do this by removing the speaker wire from the amplifier and get a normal battery, a AA battery from a remote control will do. Hold one of the 2 speaker wires on the battery and tap the other end of the batter with the mate speaker wire - you should hear a 'popping' noise which indicates they work.
2. Ensure the 2 main speakers are connected to the "A" terminals on the amplifier ... or the "Front" terminals.
3. Make sure you have selected to use the "A" speakers on the front of the amplifier
4. If none of these work but your headphones still work, you might have blown your fuses, which are located on the back of the amp.
5. if none of the above work, chances are you have blown the channels on your amplifier, which is not all that expensive to fix.
Jason
January 2008