I don't know why, but all of a sudden the treble on the Denons are beginning to bug me. It's becoming very fatiguing to listen to. I've had these for more than a year and they've been burned in for a while now, so I know the sound isn't changing. Can anyone recommend headphones (<$500) with a...

Hi all, Can anyone comment on the sound quality of a Zero Dac (default opamps, first version) versus a sound card in the sub $150 range? Here's the thing, 2 channel speakers don't really do it for me and I love being immersed in a surround setup. Right now I have a set of D2000s running...