Speaker / Amp Wiring

   I am trying to wire the system in by boat.  I have 4 6x9 speakers (Pioneer) on the tower.  The tower speakers are wired in parallel (left side and right side).  I also have 4 stock 6-1/4 speakers in the boat.  These are also wired in parallel (left and right). Then I have a 10" MTX subwoofer.  My stereo has pre-amp outputs.  Overall I have 8 speakers and 1 subwoofer, but it comes down to 4 2ohm speakers and 1 sub because of the parallel wiring.  How do I properly power this set up without frying the amp(s).  I had a 5 channel amp powering all of this, but it could not handle the output.  I want to purchase more / different amps, but not sure which way to go.  Can someone please help me with this??

I have been told that I should separate my amps.  I was looking to purchase 2 or even three amps to power the system.  I fried my last 5 channel amp with all of the speakers.  It could not handle all of the speakers.  Is this the way to go ( 5channel), or should I purchase separate amps?  Are there specific amps that you recommend??

Thanks Rushman and forbidden. 

It seems that everyone believes that a 5 channel will be sufficient to run the system.  What happened with the other amp was that it would constantly overheat and shut down.  Once cooled off, it would kick back on again.  After the last overheat, it wouldn't come back on again.  Found out that it is now blowing the main fuse (30A).  So, I think that it just overheated too many times and is now shorting somewhere in the unit.  It was an old MTX 5 channel and probably should have been replaced anyways.