Just thought I'd share some short impressions. I tried them out at my local store today, and immediately bought a pair after hearing them. (Although I got it for a friend who was looking for a pair of earphones in this price tier)
Build quality is fantastic, you can clearly see the beautiful walnut grain on the shells. Cable is sturdy and supple, and not stiff at all.
Sound - the clarity for a pair of earphones at this price range is astounding. Vocals shine through the clear and articulate midrange. I would say note thickness is very well balanced between clarity and lushness. It is thick enough to be engaging but not too thick as to obscure detail and make voices feel muffled. Bass is punchy and quick, yet retains enough impact for an enjoyable rhythmic experience. It is also tight, with a fairly linear sub to midbass frequency. There is just enough midbass to feel the body of the bass without slowing down the pace.
Treble is quite refined and tuned to supplement the mids and bass. It is never harsh nor fatiguing, but retains enough sparkle to enjoy rock songs. This iem handily beats anything I've heard in this price tier, and throughout the audition I just kept thinking how well tuned the 12 classics were.
Staging is not the widest or deepest at this price tier, but slightly larger than average width coupled with decent depth and height to make it sound immersive. Layering and detail are average for an iem at this price tier, but the resultant sound is pretty engaging, giving a pretty immersive experience. I would prefer more depth for immersion but that's just being not picky.
All in all, consider me impressed. I would heartily recommend the Meze 12 classics to anyone looking for a universal iem at this price tier.