So we now have a speaker with >5% distortion which isn't audible subjectively. Is a SINAD of 96dB poor?

[Frank Dernie]

It’s for sure the the vast majority of what matters.

So I have read, though it doesn't (entirely) agree with my experience. The first speakers I built, 52 years ago, using a Wharfedale 8" RS/DD drive had awfully peaky FR but didn't sound as bad as it looked, probably because the resonances were so high Q they were almost never excited by music.
Also getting clean bass from a speaker has been a key parameter in choosing for me and there are big differences, and I don't mean due to the room (otherwise the bad and good would have suffered the same).
I have read 2nd harmonic bass distortion is fine but I, personally, hate frequency doubling, as it used to be called.

 

[vavan]

would choose a tone towards the bottom of that range (but not within the roll-off of the crossover filter) and another towards the top. Maybe 400Hz and 1500Hz, say? You'll need to select the "custom" option in REW for this. Place the mic near the driver you're testing. The RTA window settings won't be important, as you won't be windowing this measurement (instead you're going to minimise the effect of reflections by keeping the mic close to the source and far from reflective surfaces). So you can just open the generator, generate the tones, and hit "record" in the RTA window.

finally found some time to do that and even more

 

[vavan]

No pressure

see my recent post

 

[vavan]

found some time to do that

just noticed that apparently I choose inappropriate RTA window setting (rectangular) despite warning in REW help: "Good choices in order of reducing side lobe level are Dolph-Chebyshev 150 (side lobes 150 dB down), Blackman-Harris 7 (side lobes 180 dB down), Dolph-Chebyshev 200 (side lobes 200 dB down) and Cosine sum 9-235 (side lobes 235 dB down). Do not use the Hann, Blackman-Harris 4 or Flat-Top windows"

anyway IMD for suggested 400+1500 dual tone seems rather big to me