The HiFiMAN HE-400s Planar Headphones ($300) may be the best sounding headphones you’ll ever buy. The planar drivers and open back of these headphones deliver the clarity, detail, and sound staging of much more expensive speakers. The HE-400s feature 98 dB sensitivity which basically means they can be driven by almost any device, including your favorite smartphone. They weight just 350g or 12.3oz allowing you to wear them for extended periods without fatigue. One thing to keep in mind is that because these have an open back they will not be your best bet for listening on airplanes as you will experience some sound leakage.