SIGNATURE

Technically “Harman-neutral” as it follows the Diffuse Field upper-midrange emphasis somewhat with a boosted bass response, though not to the level of “true Harman”. Subjectively, the Oxygens sound slightly upper-mid forward with a mildly pronounced sub-bass emphasis to me, though it wouldn’t be a stretch to call it “neutral” either.

THE BAD

I don’t think that there’s anything outright bad on the Oxygen, so I’ll list down some things that you may not like with its signature.

The common critique of the “DF bump” still exists; you get a very pronounced emphasis of upper harmonics that make instruments sound more forward and possibly more intense. Note weight may be an issue if you want something rich or heavy; the Oxygen is on the leaner side and prioritises a more snappy transient response over a more “lush and smooth” experience.

Fit seems to be an issue with many ears as the lower area of the shell hangs down and comes into contact with the ear notch and the tragus, resulting in a less secure and shallow fit. It is not a problem for me, but with the number of reports I’m reading around the internet I think it’s a good idea to at least reinforce this potential non-audio dealbreaker to you.

THE Good

I have heard many IEMs that claim to have (or is famous for) a Harman-style tuning. I’m not a particularly big fan of the target myself; the bass boost is a little weird and pinna gain is way too intense for personal enjoyment. Moondrop’s own Kanas Pro, KXXS, Blessing and A8 are examples of this tuning philosophy and, while I may appreciate them as “good IEMs”, they aren’t exactly on my rotation list for personal use.

Despite this, there is something about the Oxygen that speaks to me more on a personal level than the theoretically-identical KXXS. Is it the lesser bass response? Is it the more even upper-midrange tonality? The KXXS sounds a little more “fuzzy” to me, perhaps a little warmer; overall it’s just a smidgen less clean. The Kanas Pro isn’t even in the comparison here, I wasn’t a fan from the start and the KXXS represents a clear upgrade over it.

The Oxygen’s imaging is surprisingly competent; while not completely awe-inducing it is absolutely better than most IEMs I’ve tried. Enough to get the rare tag of “above average” from me, at least. Resolution is fine, it’s no Etymotic but it digs below surface-level detailing fairly well, and does so with well-defined notes that are less smoothed over and more textured.

I’ve said that the Oxygen is one of the best Harman-style DDs I’ve heard so far and that statement still holds true after my usual critical listening sessions. Yes, the tonality is a little too upper-mid focused for my own tastes, but I’ve never really thought about the Oxygen as “fatiguing” despite this criticism. It’s a well-balanced set that doesn’t go overboard in any frequency range even if it may get a little liberal at certain points; the bass is cleanly boosted with zero smearing, bleed or anything resulting from a “dirty emphasis” or bad transients, and the treble (arguably the hardest frequency range to get right) simply exists as a cohesive part of the frequency response as a whole, neither dulled nor overly-sharp.

CONCLUSION

The Oxygen is one of those IEMs that is hard to gush over because it’s something that can be simply described as “it’s good”. It’s technically competent, it’s well-tuned and would fit most people’s sonic preferences to some extent.

The obvious question would be how it stacks with the KXXS and Kanas Pro as there is an obvious price hierarchy here, and in this specific case I’d say that price reflects performance. Though on that note, the concept of “value” is still too subjective for me to determine for you. Absolutely need that $80 discount? The KXXS is still a very respectable performer in its price bracket. Willing to go all the way for the better sound? I’d argue that the Oxygen would be the better IEM overall.