The IDQ is not going to be as loud, or have as much bottom end. But it will be more precise, easier to blend with your front stage, and will play higher better. If you have great midbass and just need killer low end reinforcement, get a Q. If you have just decent midbass and want a seamless transition between your mids and sub, get the IDQ. I like telling people the IDQ is perfect for idiots...no one can make this sub sound too bad!