I have two pairs of headphones; Sennheiser HD 600s, and Grado SR 80s. I use a Headroom Little headphone amp with them. I always like the sound of the Grado's, but when I heard the Sennheiser's, with the Little amp I was sold on that combination. I am getting a Headroom Air Head amp for the Grado's which I will bring to the office.