I bought them.
One thing I really
love about them is how JBL acknowledged that trying to reinvent the wheel in terms of HP designs is a bad idea and simply tried to copy every successful bit of design around for a pair of ANC, portable over-ears (the QC35/XM3-4 headband design, the Bose tilted earcups to provide room for the earlobe, the clicking headband, etc.). They made a few mistakes in the process (the cups don't align with the headband when swivelled flat like on the XM3/4 for example, or the yoke isn't offset like on the XM3/4) but I quite enjoyed the results. With the exception of the pleather used which feels horribly cheap and sticky. The design is dumbly great IMO, unlike what Bose or Apple tried to do with the 700 or Max with the headband to cup attachment designs / mechanisms (which in both cases ruined the headphones for no benefits whatsoever, albeit for very different reasons).
I also really like the controls. Simple, dumb, well executed.
But the main problem I had with them, just like any other pair of ANC over-ears from Harman before, is the terrible electronics. I'm not going to mind that the ANC performance wasn't superb, but I am going to mind a stupid lot when the ANC "hiss" constantly varies for no good reason whatsoever , frequently becomes annoyingly audible, and may vary asymmetrically between the left and right earcups. I also had the usual set of connectivity and operational problems I've had with quite a few BT headphones.
The SQ with ANC on was alright (without taking into account the ANC noise), as in what I've come to expect from Harman products, which is "we tried to reach our target but couldn't quite nail it once it's actually on a real human's head", ie the general curve sounds fine to me but above 1kHz it's quite uneven and peaky to the point of being tiring without EQ, and there's a general lack of care for going the extra mile to avoid these problems (the K371 is a case study of how to ruin a theoretically solid sounding pair of headphones). Thankfully the app's EQ allows you to select the frequencies you want to act on, so it's one of the few app EQ saved on device that I really enjoy using, even though the UI makes it fiddly for trebles adjustments.
I think I would have kept them if it weren't for the ANC hiss problem. Perhaps ulterior firmware updates may improve the ANC behaviour to make it more stable. Apparently it's the first implementation for Harman of that :
https://ams.com/-/harman-anc, so perhaps it's just growing pains for now.