You do have folks like @joentell who provide measurements. Joe's aren't anechoic; they are MMM in-room a few feet from the speaker, IIRC. But, that's still better than nothing. And as I have shown many times over, a spatial average does indeed line up very well to the predicted in-room response (PIR) which is calculated from the SPINORAMA data.
So, with Joe's in-room measurements we can still learn a good bit about the response above about 800Hz or so (where the room no longer is a contributing factor for the majority of speakers). For example, if the MMM yields a flat response rather than sloped down then we can assume the sound might be a bit bright. And we can see crossover directivity errors from mid to tweeter.
So, with Joe's in-room measurements we can still learn a good bit about the response above about 800Hz or so (where the room no longer is a contributing factor for the majority of speakers). For example, if the MMM yields a flat response rather than sloped down then we can assume the sound might be a bit bright. And we can see crossover directivity errors from mid to tweeter.