Why do you guys pursue a flat frequency response when you buy a subwoofer?

If you wan5 fast responses check out the Svs 3000 or ultra 16 
they have 52 bit processors built in and monitor any variations 
in milliseconds and are superb with split shaft voice coils Great app and a bunch of other things including free shipping 
and 45 day satisfaction or full money back . I hav3 the SB 3000
for $995 or 2 for $1900 delivered. It best my $1700 JL audio sub 
and beat any Rel it is the only great sub with an app the split pole voice coil works only 5he inner part at low volume which is very tunefull, when more power is needed uses the larger outer part 
of the voice coil and goes down to a true 18 HZ.

@audiokinesis , Many hardcore audiophiles i know stick with 2 channel music systems, a.k.a, their high end turntables, DACs, integrated amps/monoblocks, etc with no bass management. These guys try subs and abandon them because they can't get it to integrate right. Many of them buy RELs because it is "supposed to" integrate better (tribal hearsay). But, when they realize that the RELs were hype but lame on delivery, they abandoned them as well.  I sure would not want to add another adc/dac into the chain with a subpar DAC on something like miniDSP for bass management (when i have a Denafrips DAC in my 2 channel setup). Guys i know have waaaay more expensive speakers, DACs, monoblocks, etc on their 2 channel music setups than i do. They are probably not gonna do that either. It's almost like there's a huge disconnect here.

But, of course, once you taste the ecstasy of a well-integrated sub, it's really hard to go back to music without one.  I often find myself listening more in my room1 with active bass management (on my Yam A3080 receiver with the Jungson Class A preouts) than in my 2.2 room2 setup. There may be room for improvement or i may never get there with the tools I have in hand for room2. 

This might be a gross assumption. But, i think some of these 2 channel guys have waaay more cash to throw at a sub manufacturer than the average guy buying a sub for his hometheater. So, It may be a loaded market chunk which is out there i.e., if a manufacturer chooses to tap into it and cater to their systems better (monopoly for sure). More DOFs or.... whatever the R&D/solution may be to better integrate them...you would know better. 

I understand, I still have my original M&K Volkswoofer and Satellites. They still play in my office. I had the Volkswoofer amplifier and driver surrounds renewed last
year. They sound as good as I first remember them and bought in 1983.
I will say though, they don’t shine a light on my primary system.

Deep_333 wrote: "Many hardcore audiophiles i know stick with 2 channel music systems, a.k.a, their high end turntables, DACs, integrated amps/monoblocks, etc with no bass management. These guys try subs and abandon them because they can’t get it to integrate right."

Very interesting. To the best of my knowledge I have yet to have a subwoofer system customer fail to get satisfactory integration with his mains. In most cases they run their mains fullrange and then blend the subs in. Therefore I must give credit to the off-the-shelf Dayton Audio amplifier I use, and to whoever designed it:

https://www.parts-express.com/dayton-audio-sa1000-subwoofer-amplifier-rack-mountable--300-811

Deep: "I sure would not want to add another adc/dac into the chain with a subpar DAC on something like miniDSP for bass management (when i have a Denafrips DAC in my 2 channel setup). Guys i know have waaaay more expensive speakers, DACs, monoblocks, etc on their 2 channel music setups than i do. They are probably not gonna do that either. "

You bring up an excellent point: How do we roll off the bottom end of the mains without any undesirable side effects? Not sure there is a totally transparent solution.

Therefore when I design main speakers with subwoofers in mind, my mains do not need a protective highpass filter unless extremely high SPLs are desired. Their inherent bottom-end rolloffs are intended to blend well with the variable 4th order lowpass filter of that Dayton amp.

Deep: "It may be a loaded market chunk which is out there i.e., if a manufacturer chooses to tap into it and cater to their systems better (monopoly for sure). More DOFs or.... whatever the R&D/solution may be to better integrate them..."

I hadn’t really thought about it in terms of degrees of freedom until this thread. I think there may well be a correlation between (useful) degrees of freedom and good integration with the mains. Lacking the financial resources to develop my own subwoofer amplifier, I count myself lucky Dayton makes an amp with a parametric EQ and a fully adjustable phase control.  My individual passive subs have some adjustability as well.

Duke