If the usual cheap earphones aren’t good enough for you, Etymotic Research has just released its range-topping MicroPro Series earbuds in the form of the ER•4PT, made for audiophiles and sound engineers. Just to make sure you get your money’s worth; each set of headphones comes with a channel-matching compliance graph signed off by an Etymotic engineer who personally tuned the balanced-armature drivers. The earbuds are capable of producing up to 122dB of maximum output, offering a frequency response of 20Hz to 16kHz. The company also offers a custom fit option to have the earbuds tailored to a given ear shape. The earbuds ship with a 0.25-inch adapter for home audio systems, as well as an airline adapter for international flights that don’t support the 3.5mm jack. You can pick up these earbuds now for $299.