Thank you TWL. I surmise that current "state of the art"
is bottlenecked at the woofer itself. I am unaware of any
audiophile-quality woofer with an X-max of , say, 30cm.,
regardless of cone material, power handling, etc. I acknowledge that there are several methods, some sucessful,
such as you described above, to extend the bass. Until a
better woofer becomes available, I think I'll comb more thoroughly through the responses of others here, and at other sites. Another thread topic could be the pro/cons
of using, say, two 8" woofers vs one 12", comparing total
cone area, X-max, air displacement, total voice coil winding,etc. (physical ability to create sound waves).
Something like comparing one large intake valve to two
smaller valves, in an engine.