NwAvGuy Northwest Audio & Video Guy Objective Reviews & Commentary - An Engineer's Perspective corrects IE6 width calculation July 21, 2011 SOUND QUALITY: The O2 is a small unique headphone amp that compares well in listening tests with much more expensive gear. Are you tired of worrying if you’re getting the best sound from your headphones? Does your iPod or Clip+ fall short with your full size cans? Perhaps the portable amps you’ve tried can’t properly drive your AKG K701s? You might want to keep reading. THE PROBLEM: I go into more details later but if you look at what’s available in headphone amps it’s not ideal. Very few have credible performance measurements, nearly all the portable models lack enough ou...