There are also good reasons to keep a higher x-over point, regardless of the main speakers' low end extension. First among these reasons is that properly placed subs (i.e. near the room boundaries) will (with very, very few exceptions) produce much smoother in-room bass response than main speakers (which are usually optimally placed away from room boundaries). In the rooms that I've measured, this will be usually true to up above 150hz, and has always been true to a minimum of 70hz to 80hz, regardless of passive room treatments, which have never been effective -IME- below this range.
One caveat: If you EQ your subs, the analysis changes a fair bit.
IME, you'll probably do better leaving the x-over point at 80hz than lowering it - and the bottom 2 octaves should sound pretty similar to what you're getting now. However, if your system allows, lowering the crossover point for a trial comparison test certainly can't hurt.
Marty
One caveat: If you EQ your subs, the analysis changes a fair bit.
IME, you'll probably do better leaving the x-over point at 80hz than lowering it - and the bottom 2 octaves should sound pretty similar to what you're getting now. However, if your system allows, lowering the crossover point for a trial comparison test certainly can't hurt.
Marty