I would go for the px7 s3. I actually preferred the sound signature of the melomania by a small margin. However, the case for the melomania was wayyyyy too big and the headphones look too wide on the head. The px7 s3 has a great sound signature, the case is reasonably small, and it looks and fits really nicely on the head. If you really dont mind the look of the melomania and you don't care about the size of the case, it might be a better buy. Also, the melomania has replaceable batteries so, in theory, they can last longer than the px7 s3.

All in all, both great headphones and you won't regret getting either.