From JL website: JL SLash serires amp
The "Intelligent" portion of the R.I.P.S. System is a circuit that actually monitors output current to optimize the amplifier's output power over a wide range of load impedances (1.5 ohm to 4 ohm per channel).
Conventional amplifiers are designed to produce optimum power at a particular impedance (2 ohm, for example). When asked to run above that impedance (say, 4 ohm), these amplifiers lose power (half their power from 2 ohm to 4 ohm). This will not happen with a JL Audio “Slash” series amplifier because the R.I.P.S. System detects the actual impedance being driven and adjusts output rail voltages to deliver optimum output. The entire process is seamless, automatic, and results in incredible dynamics for satellite channels and consistent power output for a wide range of subwoofer configurations. It also takes into account the real impedance of the system, rather than relying on often inaccurate assumptions based on a speaker's rated impedance.
The bottom line of the R.I.P.S. system is: Optimum power, at any impedance between 1.5 ohm and 4 ohm per channel, at any vehicle voltage between 11V and 14.5V.