Earpads for HD 600 series

Definitely worth getting OEM pads, the feel is much better than anything else you'll find cheaper. Also the sound quality with OEM pads is justified, very happy with them.

Annular Earpads with Foam Disk (pair)

Wears down very fast and will probably replace them at least twice a year

My old earpads and foam were falling apart when I realized I could replace them instead of buying new cans. Sennheiser Canada delivered fast, and not only are the renewed headphones more pleasant to wear but I even think the sound is smoother in the midrange.

The sound is now as great as it was years ago.