Great headphones overall. I bought an open-box pair to get a better price and they were in a like-new state, I couldn't tell a difference. I've had no build quality issues so far.
The sound quality is fantastic when hooked up to a proper DAC & Amp, perhaps my only complaint would be the relaxed midrange, but that can be fixed with EQ. Highs are clear, and bass is well delineated. Soundstage and instrument separation are not exceptional but are not lacking either. They're revealing enough to scale well with better equipment.
In terms of build quality and comfort, the metal build seems durable but is a bit heavy, I would say I can wear them for ~2 hours but not more than that without taking a break. The cable is also disappointing but can be replaced with a custom one. All that aside, these headphones are terrific for the price and I can recommend buying them open-box as well.