Thanks idc. My comment was more along the lines that if hissing is normal for sound cancelling headphones, then why does 1 pair not hiss? They are identical headphones apart from that.
Both pairs do cancel sound, however if they can make one pair without a hissing noise, why can't both pairs be like that?? Far nicer not having the hiss noise, so I want both pairs to be like it.
Awaiting the second replacement pair currently.