From Etymotic’s newest lineup of acclaimed IEMs, the ER3SE and ER3XR use high-performance, precision-matched balanced armature drivers. These high-sensitivity IEMs are a great match for mobile sources like your smartphone or portable digital audio player. For those who prefer a stronger low-end response, the XR version delivers a modest bass boost over the SE. Headfonia reviewer Lieven says, “If you know that custom IEMs most of the time offer a -26dB isolation, then you immediately know these Etymotic IEMs are very special. These ER3 and ER4 IEMs simply are the best isolating IEMs in my collection. Actually, they have the highest documented noise isolation of any earphones or headphones on the market today. Very impressive!”