Speaker relative efficiency/sensitivity when using a high pass filter

@erik_squires --

"100 Watts is not enough, but it is enough.. ... but you can't tell by wattage... Funny."

And we also read and make of it what we want to, right? :) As I'm sure you can assess from my original reply I'm not, depending on the context, in complete disagreement with you, but that's not to say I refute myself. I merely try and point to scenarios where 100W can be more effectively utilized (if still not being "overkill" per se), but those are scenarios outside of your context, and so my main contention still holds. 

In pro this comes up in "bass managed" speaker placement in ATMOS systems.  When you roll out the bass of a small speaker, how much does the total SPL capability change?  The answer is you have to measure it.  We did so at the ATC factory and it only gains around 1dB total output SPL to use a HP filter (bass management).  There exists out there some manufacturers that state massive improvements in SPL when bass managed, I'm not sure how they arrived at these new measurements and conclusions.   So I think from a practical standpoint, you'll get a little improvement in total SPL by filtering out LF, but its less than you'd guess. 

@nymarty I am using a Devialet 400.  It has high and low pass filters along with time delay. I have a Dayton Audio SA1000 as my subwoofer amp with second order and fourth order high and low pass filters, respectively, at 80Hz but I am not currently using these. I would if I were to go with separates or an integrated with a tape monitor.  I'd lose the time delay feature of the Devialet but would hopefully make up for it with other attributes.  I could also use a miniDSP or equivalent which you might consider as well.

@lonemountain Do the small speakers you measured have considerable bass output? I would guess that a speaker that goes to 50Hz would yield less of a gain than one that goes to 35Hz. 

@tcutter Thanks.  Might have to try a miniDSP. Good luck with your setup.

Similar but different question: with crossover (12 db/octave) at 200 Hz, how much (percentage) of the power goes to the low pass, how much to the high pass? 

Background: trying to determine (for class A or tube) what power rating for the amp I should eyeball for the high pass.