The Sennheiser HD 555 headphones are great—so great that I’ve neglected to upgrade for many years. Thanks to a discovery by clever human being Mike Beauchamp, it turns out you can perform a free upgrade to these headphones and make them equal to their high-end counterparts.
from Lifehacker http://feeds.gawker.com/~r/lifehacker/full/~3/gifAhvy_4-E/upgrade-a-pair-of-mid-range-headphones-to-an-audiophile-1456454424