Not to disappoint you too much, but the 1000 watts advertised is just marketing hype. If your amp is the PB781X, it should have only a single 15A fuse on it. Your battery provides 12.5 volts when the engine is off, so at most, your amp draws 187.5 watts of power. Draws, not outputs. No amp is 100% efficient due to heat. When your engine is running, assuming your alternator outputs 14.4 volts, your amp's maximum power draw is about 216 watts. Again, this is what your amp draws, not what it puts out. What you should focus on is the RMS (continuous) output, not Max or PMPO. Those numbers are useless, unfortunately.
Your amp is rated to output 50 watts per channel at 4 Ohms, and 75 watts per channel at 2 ohms. This is when wiring your channels separately, not bridged. I did not see true power specs for your amp while bridged, but it's possible you'll just get the full 150 watts to the single bridged output. Do not attempt to apply a 1 ohm load to your amplifier, as you will run the risk of damaging it. It's not designed to handle a 1 ohm load. If you're lucky, you'll blow a fuse before the amp is damaged, but either way, there is nothing to be gained by attempting it.
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