I liked the sound of the drivers, but if I moved my head a bit, or bent down to look at something (like maybe a mixing console), one or both of the earcups now become a bit looser, and pull away from my ears, not a lot, but just enough to change the sound. If I push a tiny bit on the earcups, exerting more force against my ears, the headphones sound much better. I did not keep these. Once again my SONY 7506's are still my reference headphone. I am about to try some Beyerdynamic DT-770 Pro-80 headphones. It'll be interesting to see how those compare...

If you're in the market for a high quality, reasonably priced, headphone amp, start with the Matrix M-Stage (and you may never need to go any farther). I recently (April 2014) visited the AXPONA audio expo in Chicago (what a great expo!), and auditioned numerous headphones, and headphone amps. One of my favorite headphone amps was the Woo Audio WA7 Firefly. But at around $1,000 it wasn't in my budget. Which brought me to the internet, in search of a stand alone, possibly Class A operation, headphone amp, with good reviews. Something that maybe...