@ernestcarl,
@thewas, thank you for your input. Indeed I measured in a single position, single pass for each speaker. I am a "head in a vice" listener, that is, I stay still in the center sweet spot when to listening to music. So I assume that averaging over an area may not be so relevant in my case? (correct me if I am wrong)
Also I don't plan to listen loud in this office system, for that I have my main system, and even there I usually don't listen loud. So max SPL for these KH 80 DSP is not really an issue. I adjusted -9dB on a gain before the EQ, and the speakers have limiting, so I am not worried about clipping. Just for testing, I tried maximizing the volume of the RME ADI-2 DAC, using the lowest gains in the KH 80 DSP as I wrote before, and even listening to bass heavy electronic dance music, still it was loudish enough for me (should have measured how many dBs, I forgot, may do so later). But the point is: I rather have a fuller sounding bass at mid to low levels than worrying about loud volume distortion. Good enough compromise for me.
And finally, I checked by ear playing around with
sine waves and the frequency slider while seated in the sweet spot, sounds pretty linear to me, so I am happy.