Only spent about an hour with the PK3 now, but it seems clear the M2C and the PK3 are two different things: the PK3 are bright, while the M2C are relatively laid-back in comparison.
A notable aspect about the M2C is that, along the frequency range, they don't really do any single band particularly well in relation to the others. The lows don't stand out from the mids, which don't stand out from the highs, which don't stand out from the lows. Thus the M2C seem pretty well balanced – although vocals, after a few days' use, do still sound a bit nasal, but not much.
I've only just got the PK3 so it's hard to say much about them, but compared to the M2C, they've left a pretty mediocre first impression. The detail is roughly the same between them, and the bass is somewhat similar in quantity (haven't much compared the quality yet), but like I said, the PK3 sound a bit too bright, and the soundstage isn't as expansive. Then again, the PK3 sound a bit faster than the M2C, and they do vocals slightly better. Overall, the PK3 at this point sound like a good pair of earbuds, while the M2C have a different type of sound, one you'd expect from fuller-size phones (within reason).
The PK3 are smaller and slightly more comfortable.
My problem with the M2C is that the soundstage, while really good in giving a sense of width, doesn't have much depth at all. In fact, the M2C soundstage would be well represented by a line drawn from the left ear to the right ear and extended 20 cm at both ends. That's about what you get.
Between the PK3 and the M2C, it depends on what kind of sound you like. If you want bright, the M2C doesn't do as well as the PK3. If you want balance (for a reasonable price), get the M2C. If you can get the M2C for ~$30 via a group buy, get them regardless. For that price, they're awesome; for $47 (bought individually), they're pretty good, at least in my opinion.
(I don't use the foamies.)
so hard to decide between pk2,koss portapro and blox m2c!
