Tim,
We do have a pretty good idea on the OP's preference for bass levels, he has a pair of SB1000s and is not satisfied. To get a significant feeling of increased volume, he needs to pick up 10db. Adding two more SB1000s will only net him about 6db (again, because we are not co-locating). The PB-1000 a little more. Two Seaton Submerssive HPs are capable of 115+ db at 20hz without room gain. By 30 hz, we are well over 120db. We do know this will keep up with his current speakers as well as his future speakers.
Audiorusty,
You make an excellent point about the phase issues with vented subs. While a well designed vented sub can have virtually the same transient response as a well designed sealed sub, the vented has far more phase change through its range. Sealed subs are easier to integrate, especially with multiples.
We do have a pretty good idea on the OP's preference for bass levels, he has a pair of SB1000s and is not satisfied. To get a significant feeling of increased volume, he needs to pick up 10db. Adding two more SB1000s will only net him about 6db (again, because we are not co-locating). The PB-1000 a little more. Two Seaton Submerssive HPs are capable of 115+ db at 20hz without room gain. By 30 hz, we are well over 120db. We do know this will keep up with his current speakers as well as his future speakers.
Audiorusty,
You make an excellent point about the phase issues with vented subs. While a well designed vented sub can have virtually the same transient response as a well designed sealed sub, the vented has far more phase change through its range. Sealed subs are easier to integrate, especially with multiples.