Your image isn't loading for me but let me give you some advice. Speakers are essentially electronic resistors. You can't just add them on to an amplifier and expect everything to be all hunky dory. A 2ohm load is the most your average amplifier can handle. If you put another 2ohm subwoofer in parallel you'd be looking at a 1ohm load which given a short amount of time will probably fry your amplifier. You could wire it in series to give your amp a 4ohm load, but then it will be producing half the power it was with the 2ohm load. Do some research on "impedence" "ohms" "parallel" "series" to learn more about how speakers and amps interact.