Right Iasca specs are for when the amp is in a sound-off competition using iasca rules, and they declare what power the amp is, so smaller is better. For actual power output, take the RMS value, realise that by the time the power gets to the amp its never 14.4 volts and is usually slightly under 12 volts unless your using power caps. So RMS value devided by 14.4 then multiplied by 12 will give you a real power output. Unfortuanely PG are one of the only manufacturers who give real power outputs anyway, must use peak power levels which are a load of BS. Quickest way of finding out how powerful an amp really is: Total ampage allowed by the fuses. Example a amp with 2x20 amp fuses is a 40amp amplifier and will give a maximum output of about 480 watts rms.