I knew they had a lot of mid-bass. I'd say the mid-bass is about +3 to +6 dB too high around 60-100 Hz, but that is likely entirely my room, not the speakers. I think the measurements came out about to my expectations: nothing particularly bad, maybe a bit heavy on the bass. But I like a bit of extra bass, so that's OK with me.
JBL rates them down to 40 Hz (at -6 dB). I would say my in-room is closer to 35 Hz, maybe 30 Hz @ -6. I did not stuff the ports. Maybe that would help with the bass bump.
The upper frequencies are really flat (those are mostly speaker, not room) and balanced. I'm not sure what's going on with the 15 kHz drop-off (is it airplay, the preamp, the amp, the speakers, the mic alignment?). I've done measurements of the C30 preamp and I know it does not drop off until after 20 kHz, so it's likely airplay or the speaker/mic alignment. The speakers are on one side of the dining room table, with the tweeters pointed up at an angle (as per the JBL stands) and the mic is sitting ear hight on the far side of the table. The 15 kHz drop could just be that alignment -- I'll try some more measurements to see if that's the case (maybe try a 1-m direct on alignment).
I find the speakers very enjoyable without a sub. I only measured at one spot (midway between the speakers, maybe 2m triangle, give or take a bit), but the sound is good throughout the dining room and the kitchen. This is entirely casual listening, either low background music or loud music while cooking.
They look great with the vintage McIntosh stack I put together, especially with the orange grills (boy, those were hard to get). I also have the blue grills, which look very nice too, if that fits your color scheme better. The angled stands keep people from resting things (i.e. drinks) on the speakers
