At less than 1 nanometer, the diaphragm of the HiFiMan HE1000 planar magnetic headphones (hifiman.com) is the thinnest ever made. An asymmetrical magnetic circuit powers the diaphragm and helps eliminate virtually all sonic distortion. The headphones, which are priced at $3,000, also feature an open-back design and ear-cup grilles made from lightweight alloy. They deliver a lifelike soundstage and an abundance of high-frequency headroom capable of registering musical nuances lost by headphones with less-efficient designs. The comfortableness of the calfskin headband and velour-lined foam ear pads will invite long listening sessions.