When bridging or running an amplifier in its max pwer mode, in your case 2Ohm mono, you reduce the headroom of the amplifier. The amp is drawing a higher % of amperage from it's power supply. So, taking away the reserve power results in an amp that is always working at like 80% for example, and can't accurately reproduce a wide dynamic range== Less Headroom for dynamic peaks of bass or any material for the matter.
This is my 0.02, and what I have been taught and living by.
Good Luck,
Chris
