"Not posting this because I'm too lazy to research, But I can't seem to find much in the line of a fair quality "Mid-Subwoofer." What I'm speaking of would not be a Subwoofer for home theater, but rather a separate Mid unit that will produce a very clean, tight, powerful and fast punch in the chest with music only. "Specifically Hard rock.""
That's because what you are asking for is not a sub. The frequencies you are talking about are handled elsewhere in the system. You don't list the rest of your system, so I can only guess, but if you have speakers that are capable, an amp would probably be the best way to fix your problem. But that's a complete guess because I know nothing about your system and how its set up (including room dimensions).