I have read that 80Hz is a good point. Being new to subs in the HT context (I used to do live sound mixing) I am just worried about the clarity of the sound between 60 and 80Hz. At the clubs/halls I used to mix at, this was not such a problem due to the enormous power and sheer volume of air being pushed by the generally overpowered systems. Especially since we generally had 3 and 4-way systems (2.1 and 3.1, I suppose!)so all frequencies were send through outboard crossovers with very specifically set pass points. For HT/Audio, I will be a little more sensitive to such things.
