Add a HD650 Headband . Either attach it removable with some velcro ties or if you don’t mind use double sided stick tape. Of course You could also stick the HD650 pad to one of these (wool) sleeves so you don’t risk leaving any stains on the original headband.
Most of these sleeves are for slim headbands. The hifiman one is quite thick, even had to stretch the wool sleeves for the 400se I had.
Probably many others will suggest dekoni nuggets…
This one looks similar to yours
or as an alternative from the 500er series. comes already with some 3M stick tape.