John,

Flipping the phase switch doesn't help with the slap/punch. And I'm dialed in so that at the cross-over frequency, I have the exact same SPL out of my 80s as out of the 600.

Transparency is hard to explain but it's like the effortless lows coming out of a pipe organ. I have been wondering the last few months if it is possible to have transparency AND faster attack/decay/tighter punch all from the same sub.

My 600 hits me in the gut and below but never in the chest and head if you know what I mean. Does the 400 hit you in both places?

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated