Are the earpads replaceable?

Yes, the earpads are replaceable. As with many other headphones, each pad has a thin flange around the edge. This flange slips into a slot along the outer edge of each earpiece, and you install the pad by slipping it into a notch and spinning it around until the flange threads into the notch all the way around. The notch is very tight, so you have to work with the flange slowly and gently.