These have digital inputs which means it has a DAC and given these measurements would possibly mean it has a DSP equalizer?
That's very likely, yes. EQ is cheap, so it makes sense Neumann would use that to improve the response, especially in a $1K speaker. I expect most active speakers to have some kind of integrated EQ these days. There's no reason to leave performance on the table by not using it.
Isn't there a way to tell if there is DSP equalization by looking at the off axis response?
No. Why would you think that? DSP changes on-axis and off-axis response in exactly the same way. It cannot change one independently of the other. In other words: DSP cannot affect directivity.
Not to take away from what they have accomplished but would you consider this cheating since it would be like a passive speaker with DSP equalization leading to a ruler flat result?
It's not cheating. This is precisely what every single speaker manufacturer should do: use all the tools at their disposal to make their product better. Yes, passive speakers can't do that (or at least not as easily). That doesn't mean active speakers are "cheating". It just means active speakers are a better technology.
Also, couldn't we get similar results with less expensive speakers and DSP?
In theory, yes.
In practice, you can't use DSP to fix directivity, so you'd still need a speaker with excellent directivity to get close to this one. The only way to achieve good directivity is through better acoustic design (i.e. waveguides, cabinet shape, etc.), which usually doesn't come cheap (though there are notable exceptions).
Also, using DSP to fix a speaker response is far from trivial and is not really something that the average user would have the time/motivation/skills to do. You would need to set up the DSP itself, and more importantly you need to obtain precise anechoic measurements of the speaker so that you can invert its response (you cannot do this by measuring it in-room, because the reflections will mess up your data).
Now you could of course use Amir's measurements to do this, and some do. However I have a suspicion that you still wouldn't be able to get to Neumann levels of accuracy by doing this because, given the insane levels of precision shown in this review, I'm willing to bet that Neumann measures and calibrates
each individual speaker at factory, whereas you would only have measurements for the unit that happened to have been measured.
What's the drawback of DSP?
EQ peaks require the speaker to work harder, potentially reducing its maximum output level. However this is also something that can be measured and accounted for, and it is (see Amir's distortion graphs).
I believe I read somewhere DSP may have an issue with port resonance when listening off axis?
Resonances would show up on measurements. Do you see a resonance in Amir's off-axis measurements? No? Then there is no problem.
This is the beauty of accurate, thorough speaker measurements: what you see is what you get. It doesn't matter if there is DSP, what material the cabinet is made of, what the drivers are, where the port is, etc. The measurements show you the end result that you will hear, and that's all that matters. Spend $X, get this response. That's it.
