Audio Systems: amp is on, but no sound, amp input, rca cable

Question
I have an 800 watt Sony amp hooked up to 2 12" Kicker comp vr2's.  The system hasn't failed me yet, but today, my subs quit producing sound.  I checked the amp, no protection lights on, all wires hooked up correctly, green power light is on.  There is no sound coming from subs though.  Took out head unit to make sure rca cable for amp input were connected.  Still no sound, any advice?

Answer
Hi Jason,
One of two things spring to mind.
One; power from head unit on signal (acc)lead, check voltage there, usually the Centre of the three, (power, signal, earth). try a bridging wire from live to signal see if the amp fires up.
Second is that either the head unit is dead on the output  or the speakers are blown (straight check with ANY speaker will test this the quickest way).
Can you get your hands on a similar head unit for 5 minutes and swap over to see if that fires up the amp?