Well, finally getting a straight down MMCX cable (just a disclaimer this one was really quite a cheap cable, so it's affect on the sound may be considered an issue for some), I'm giving the 15mm detachable earbud a try with no burn in so far. Keeping in mind that my tastes lean towards a more bass-centric sound, the bass is light compared to the mids and treble. I'd have to dig it out of storage, but from memory it reminds me of the Ety HF5's bass. Vocals and instruments feel nice and clear, and Beethoven's 7th Symphony Allegretto (my copy is a vinyl rip of a 1964 performance, so not perfect) sounds really quite lovely, but not going to have the instrument separation of something like the Rose Mojito. Nobuo Uematsu's Opera Maria and Draco off the Distant Worlds album also sounds really quite solid, so I'm guessing this earbud would be well suited with classical and maybe something like Tom Petty's Wildflowers album.
So, based off initial impressions, for $25 (which doesn't include a cable) I'd say it's a fairly solid earbud for classical music, but felt lackluster with Radiohead's Nude off In Rainbows, so more bass oriented music won't have the weight it deserves. Honestly, I was expecting a bassier sound from a 15mm driver, but vocals and many instruments sound actually pretty good.