I bought them for my Audio Technica ATH-M50x. I didn't notice any difference in sound quality. They are comfortable and very durable, they are still in good shape after 8 months of using them.
The only downside is that my oily skin gets absorbed by the pads, it's also harder to clean than leather. I use the headset for longer periods everyday, around 5-10 hours, sometimes even more. I still recommend them but if you have oily face try to clean them often.