Had to bin my Sennheiser HD540 Reference nearly 2 years ago for the same reasons. I have searched for a replacement for quite a while. I also tried Grado, Beyerdynamic, Audeze. With hindsight, I fortunally had the pleasure of hearing the Sennheiser HD800. Although they need quite some time to break in, now I am happy as I can possibly be. I also use a Mac with an extensive collection of classical music of all sorts. I use iTunes and Amarra as my players of predominantly lossless files, use a Audioquest Dragonfly 1.2 as headphone amp (for the time being as I am in the process of finding an alternative.).
In this set-up, many recordings of the KCO at the Van Baerlestraat Concertgebouw hear and feel like being there in person. This feature alone made the investment in the HD800 one of my best personal decisions so far. I wish you the very same experience regardless of the choices you make in your quest for a replacement.
