This allows the user to use any device that has RCA output with the amplifier, instantly giving the P400-2 a large amount of compatible devices that the P300-2 cannot use. The DSM technology of the P400-2 allows the circuits of the amplifier to work more efficiently. It does this by utilizing 1% tight tolerances, and decreasing cross-talk between other discrete components. It also has the side effect of lowering the operating temperature. The P400-2 also features differential inputs, which eliminate noise picked up by signal cables. It does this by measuring the voltage of the positive and negative inputs, taking out anything in between. This greatly enhances the sound quality of the amplifier.