I have used Optima batteries in various applications for years, automotive and marine, no problems whatsoever. I have one now in my truck, second one. First one lasted about 10 years. When I don't use them I use Interstate lead acid batteries.

The problem I have with AGM batteries in general is they require a special procedure to charge them if they discharge all the way or down very low. If you just hook them to a charger they won't charge up all the way.

I now use an Optima Yellow top (which is their Deep Cycle model) in my truck with aftermarket stereo equipment. I had a red top, it worked fine. No energy cell or extra battery.

If you are not using your stereo with the engine off, with that wattage you do not need a Kinetic or any other energy cell or extra battery. If you do run it with the engine off, maybe you should think about getting one. Just remember that an energy cell is intended for use with large electrical loads to maintain constant voltage values of power to the amplifiers. Once they discharge, your alternator now has to work to not only charge the battery but the energy cell as well.

Running any stereo system with amplifiers with the engine turned off is really hard on the battery and it also makes the amplifier power supply have to work very hard to keep a constant voltage supply to the amplifier because the voltage from just the battery continues to drop as the battery discharges. With no alternator running to charge it, what eventually happens is the power supply in the amplifier heats up. If it is driving sub woofers, that heat eventually damages the power supply enough that it fails.