The ASY are some of the best all-rounder earphones in terms of sound and comfort. They are beautiful to look at, straightforward to wear, and pleasure to listen to. Sure, they are not perfect, but easily outperform many of the earphoens on AudioBudget. The treble might not be as sparkly as I like, but it is about as comfortable as it can be without losing too much detail.
At least the meshes are sturdy and don't fall off, unlike Tennmak Pro.
NOTE: The pair I received is called Yinyoo Bellsing, which is simply an unbranded/OEM version of MDK-ESS ASY. The "ASY" logo is not written on this version.
These earphones are shaped perfectly for the ears. They sit firmly and keep a perfect seal at all times, without requiring any special tips and without having to mess with memory wires. Very wisely designed! Still, depending on your ears, make sure you use the appropriate ear tips to hear the bass properly. If the sound is too cold - change the tips.
Lows / Bass
The bass is balanced and controlled. Very similar to ASK, but seems to be less muddy. The bass is never muddy and never leaks into the mids. For my taste, I'd say that they are a bit bass-light because of the roll-off in sub-bass range, so I wouldn't necessarily choose these for bass-intensive tracks. But fur general use, that bass is a great all-rounder.
Mids / Vocals
The mids are emphasized, specifically the upper-mids. Vocals are very upfront and the sound is more intimate than ASK's. The mids are some of the cleanest I've heard so far, even with the slight metallic tint that's normal with balanced armatures, but you probably won't notice it.
Highs / Treble
Althought not as crisp as ASK's treble, the highs of ASY are delicate and calm, very controlled and detailed enough. For those sensitive to piercing highs - these highs will be perfect. No sibilance on the vocals as well. As compared to Tennmak Pro, I liked Tennmak's highs a bit more, but that's purely a matter of taste.