I own the Sennheiser HD 650's and 800's.  I've owned the 650's for going on 3 years and originally listened to them through an Asus Xonar Essence One DAC/HP amp combo which was unable to totally lift the infamous "veil."  I eventually became so dissatisfied I sold the headphones (which I almost immediately came to regret) on ebay (sold the Asus DAC, too).  Fortunately the new headphone owner wasn't happy that the outer box had no pedigree label and returned them.  Providence?  I bought the highly recommended Bottlehead Crack headphone amp with...