I've got that same JBL GTO 1200.1 running three MTX tens and its the most perfect bass I've ever had in the car. Hits clear, deep, and stays away from any notes it shouldn't be playing so I never lose the rest of the music over the bass. Plus I haven't even tried turning the power up on the amp, I know it will blow my subs and I can't afford the alpine Type R's i want just yet

I plan to get another smaller jbl amp to run the interior speakers soon.