The MS19 model has proved to be the brand's most well-balanced earphones to date. However, when it comes to the quality of the sound, there is much more to be desired, especially when there are better sounding earphones in this price range, even though they can't compete with MS19 when it comes to build quality.
The MS19 highly resamble Remax RM-610D a lot when it comes to sound signature (the frequency response is very similar), but MS19 are louder and a bit harsher, while RM-610D has a cleaner sound but also a bit darker timbre, so it all depends on your taste and budget.
As compared to the previous MS18, the MS18 have more precise and airy mids, along with beefier bass response, thus MS18 would be my pick.
The volume buttons work on Android devices. I don't have an iPhone for compatibility check.
Comfort & Fit
Using the angled shape of the housings and extremely lightweight materials, Headroom has made them very comfortable and easy to wear. I had no comfort issues whatsoever and could wear these earphones for many hours straight.
Lows / Bass
The bass is quite clean and would probably satisfy those who like rather flat-sounding bass response. Even though there's just enough mid-bass to not sound muddy, the bass still sounds a bit dry and unexciting, and that probably has more to do with the relatively weak sub-bass.
Mids / Vocals
There's generally nothing wrong with how these earphones sound. They are not the most precise, nor the most detailed, but I can definitely see myself using these while outdoors. The mids are present and non-intrusive. Can't pin-point any significant recession, it's rather flat-sounding. For analytical listening, these definitely won't do the trick. But for casual listening, these are fine. Still, if you can handle a bit more warmth (more mid-bass and sub-bass), I would still go for MS18, as I think they have quite more precise and airy mids.
Highs / Treble
The highs are mild and flat-sounding as well. The amount of detail isn't that great, but at the very least these earphones are not dark-sounding. The treble isn't highly detailed and not entirely tonally precise, and even has some hints of harshness, but that's not very noticeable. Overall, nothing fatally wrong with that treble.