Not sure what sub you have , but be fore warned, extending FR with the BASSIS eats up stroke and power, be careful.
I'm running quad Tumults with about 6kwatts in a smallish room, so it wasn't a real concern for me as they loaf most of the time.
If bottoming becomes an issue or your amp clips, just sacrafice some HZ so you don't cause problems.
Bosso can give you tips on dialing in your subs Qs and Qb, and explain things MUCH better than I.
What sub(s) are you running, and what drives them.