Just FYI, the Oxygen has an almost identical FR:For sale is a pair of Moondrop KXXS, owned for less than a week and used for maybe 10-12 hours. They are like new with no physical or sonic defects. They will be shipped in their original box with everything included: stock cable, carrying case, tips, inserts, etc.
There is a lot to like about these headphones, but ultimately their V-shaped sound signature is just not for me. I'd prefer to trade for something more neutral or warm/relaxed/dark in the same price class, like Tanchjim Oxygen. I like headphones that sound full and realistic with good separation and organic/warm timbre. If interested in a trade for something worth more or less money, DM me and we can talk about evening out the deal to make it fair with cash/other gear.
Price does not include shipping, which buyer will pay.
More photos by request!