Just scored the K371 not too long ago, used off Amazon, under 100 bucks. They've made me very happy, the sound quality without EQ is very high. The headband though, causes a painful hotspot, and the cable feels icky and cheap. So I accessorized and tricked out my pair.
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Got a nice neoprene headband pad. Also this cable is a nice improvement, not microphonic and no memory and braided, like a nice IEM cable.
I have many cans, mostly planars and almost all of them benefit greatly from being EQ'd to Harman target. Now it's all done in the analogue domain with physics, nicely and elegantly, with the K371. They're sensitive and efficient too, sound great straight out my DAP, all this at an affordable price point. My other choices were the FT1, Adam H200, and Shure SRH440. The Shures are supposed to adhere closest to Harman, but are absolute junk build quality. The cheap plastic parts almost guaranteed to fail. I'm happy with my choice.