I would say 100 hours is a must for these to show their true sound. The open box sound is not as tight as my pair. Bass becomes way more dynamic, tighter and more controlled. Mids solidifies, highs become one of the best if not the best..You think the timbre sounds good now wait till the sound tightens up. Not to mention the definition of overall sound improves. I have well over 200 hours on my pair and I can't comprehend how good these earphones sound to me. It is on a level I never expected. Don't care if any of you guys that read this don't do burn in..Burn them in, do it in secret.. It gets better and better..