AKG K550 has been gaining fans and awards as one of the best sounding closed-back headphones that does not cost a bomb. The closed-back design means sound isolation without disturbing people around you. Build with lightweight metal frames for comfortable long hour listening, AKG K550 has a low 32 ohms impedance intended for use with portable mobile devices. You can buy AKG K550 for around USD $200. It is a bargain for a clean, crisp open-stage sound in a closed-back headphones. You would definitely have to spend a lot more to get better sounding closed headphones.