I have the 15H automotive crossed at 63 Hz a aT 10C sub, 3Khz with Scan Speak d3004-602000 and revising my system.

Simulating the drivers using winisd I noticed the 18H give 'much less' bass response compared to the Scan speak 18W4531 and the Focal utopia 6w3 (high Qts).

1. Am I missing something (the system performs very well but lacks a little bit of a bass)?
2. Which setup would you suggest (I also own the Utopia 3" mids).
3. Which low crossing freq would you recommend for the 15H or 18H? Would you prefer the 18H over the 15H?
4. Thinking of adding a pair of 8" on the rears (maybe instead of the 10C).

Thanks,
B.