You can also tell from the vent pattern on the back, the A pads have 4 holes, and B pads have many holes. B pads deliver more bass and warmth in the lower mids (as well as maybe a little more upper mid presence).

I personally like the sound, some people say they sound bloated. To be fair, there does seem to be a degree of unit variation, one sample crinacle measured seems to be a fair bit bassier than the other, so it's possible my pair is a leaner sounding set.