"I take offence to that!
...
Slander is spoken; in print, it's libel."
Heard and understood, Matt
As to the frequency response graph thing - at peak output, no, of course any subwoofer won't show a flat response. But at
anything over 85dB from 1 meter? I don't think it's crazy to hope for flat response at 95dB output from that distance. If we are hoping to achieve flat response at 85dB
at the seating position then a sub is going to have to be able to output flat response at higher volume levels than 85dB from just 1 meter.
What I was saying about the sloped frequency response at higher output levels was in response to what people were saying about the VTF-2 MK3 having flat output down to 18Hz (-3dB at 18Hz). That might be the spec and it might be perfectly true! But what I was trying to point out is that - in a real room under real conditions - you won't experience flat output down to 20Hz at your actual seat. Or, to be more precise, you might at lower volume levels, but not at reference levels - the way I listen

For me, trying to have flat response at 85dB at my seat, plus trying to hit 115dB peaks, the VTF-2 MK3 started to roll off at just under 30Hz or so. I'm not certain, but I think the ports are actually tuned for 25Hz on that sub - hence having to block one port for the 20Hz "max extension" mode. It isn't at all surprising that extremely low frequency output goes down in max volume level as a result. I'm just a crazy nut who wants it ALL!