Isn't the 20.1 strapable? if so I would go with a second, higher current capability plus it is easier to mount two separate amps then one large one. Two strapped amps almost always will outpower a single large one of equal power output. But to answer your question the IA40.1 is an awesome amp, sold mine because I needed cash but I ran mine for over a year on a 16V system. On a 12V system a single amp can and will draw well over 500A at times on music and most definately on burps and at .25 ohms, well a single battery won't do it.. Polo.