I own the IE80 and I have the Momentums (kind of borrowing them) and my advice is: don't by the Momentums. It is kind of difficult to compare IEMs and Over-ear headphones, but the SQ of the IE80 for me is superior to the Momentums. Biggest flaw for me is the bloated bass of the Momentums. The bass just isn't tight and of poor quallity, it really ruins the listening experiance. There might be also a fitting problem. They are very small and they barely fits my small ears (and I have very small ears). Anyways, although they are not as pretty, the Amperiors have a better SQ and they are half the price, because they are discontinued.