In my observation Daniel has very good ears. I hope I am allowed to say that. Or maybe put differently : he was better able to discern culprits than me from my own known system. With this in mind ...
Or maybe a little bit more of toe-in?
Now, we dit NOT talk about this subject at all. But it is spot on. It is also right on topic for our "Imaging" topic here. Let me explain, and MKII owners, be "advised" ...
Up to the lowest frequencies the bass from these speakers is "pure directional". And no, I don't recall that Daniel and me were playing something that would show it (at least I did not for the purpose), but possibly he noticed anyway, and this is related to the quote above;
What I do on purpose is not let blend the bass where I observe(d) it shouldn't. Now, with 0.00 degrees of phase difference between left and right (all NOS1(s) owners have this), this means that any not exactly same initiation of left and right of bass will create a hole in the middle.
Now, sorry to be technical, but because of "electrical" reasons almost all recordings show that not being equal of left and right (for when the sound emerges from the speaker). Let me try to explain by means of the NOS1(s) itself (but I have told this in particular before) : Any common DAC will have a phase difference between left and right of about 0.02 degrees. The NOS1(a) can do this too ... just set Switch#5 up and deactive "Is NOS1" in XXHE Settings (or use another random player).
The difference between these two settings ?
No single whatever bass will sound from one speaker only never mind it really does. Actually it is so that nobody will notice really and notice that it should be tested with the "sine" like sounds only, or otherwise the higher frequency harmonics will discover the real positioning (and now you are fooled and only with good experience you will hear that the bass still comes from the middle).
The difference is only 0.02 degrees (at 1KHz btw and for a lower frequency it will even be less) but it is totally crucial. So is the distance from the two speakers to you - just saying).
What do I want to say ?
Well, that this same difference is for similar reasons how a normal DAC operates, there for the same electrical reasons. Thus, it is almost always there. What does this mean ? ... that no bass will sound from the middle because there's a small difference (delay from left to right or the other way around) that will imply "space". Just think that with DSP you will overdo this and the result is a spatious sound. BUT :
When you allow the both LF beams to merge too much, the effect goes away. Also - and very logically, with the base of the both beams having merged indeed, they will add up fully. Result ? more bass.
Aha, because I deliberately prevent that. How ? Toeing out more.
As an intermezzo I can tell it form a different angle :
This effect - of the both channels not shooting at the exact same time - is so strong for the lowest ferquencies, that the air pressure in the room fluctuates because of it. Easy enough to understand : the SPL is now oscillating with the two beams which don't fire at the exact same time. So normally there's the one frequency only (say 30Hz) and we are used to that, but when the one 30Hz follows the other 30Hz there's actually a distortion going on. And some people are sensitive for this. They go literally sick (and I really experienced that here although it was not me myself). Remedy : Toe-in.
When a woofer is distorting to begin with, there are so many frequencies in order that what's thrown at you becomes more random and the "sick" effect stays away.
I am not bothered by this effect, but *I* am bothered by the uninteresting sound coming from the speakers otherwise. It then just "does not work" any more.
So about the imaging : Try to perceive a bass from the middle to begin with (find the proper recording). Works ? Then now toe-out. Say that you move backwards the outer wing tips for 3cm each. That should do it.
If all works as it does here, you now will perceive that hole in the middle.
Really intended or not, this is how it's in the recording.
But watch closely;
You might have perecived this before and think it is no good. Most easy thinking is that it is the high frequencies doing this to you; but it hardly can because you're listening off-axis to begin with (on purpose, since the mid-high horn is above you); so, the "on purpose" is about the toeing you can now do to your liking because the nid-high will hardly impact because of on-off axis listening (it will for reflections to the side walls, but this is another matter). Thus, concentrate on the bass because it is all about that.
Less bass, but separation in it. Do call it DSP if you like. But if all is right something now starts to "work" which otherwise could not be there at all. It is the left/roght (very fast of course) movement of how the waves emerge form the woofers. It creates spatiousness.
We could say that Daniel was thus spot-on with his idea about the toeing in with the notice that we didn't try a thing with this because it wasn't brought up as a subject. But I know ... it will work. For more bass that is. Not even about more perceived bass but about it really being more (the adding up). So blend it too much and it will happen.
And I do it the other way around on purpose ...
Small disclaimer : I highly doubt whether it would have brought much difference with my Windows 7 which is not accurate in the bass at all ( way way too thick for how I DSP'd the speakers which has been done for Windows 8 ).
Anyway, MKII owners should try and I think it can be a revelation. Very easy to try as well, so let me know your findings ...