I had a pair of Sennheisser HD660S that I tried to sing over to no avail, however my new/used sony MDR-Z1R pair is letting me sing over it with my deep voice.

Can anyone shine a light on why an open back wouldn’t and a closed back is?

Also, IDK guys, the general opinion of owners is that it is the greatest you can get when your listening to anything and everything. Especially popular music.