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How much are the HD 580's?
/googles
OH yeah. ~ $300? Those better be good. hehe
What headphone amp do you have? Might get a good quality one and see if it helps these SR60s at all. Do you listen from your PC? What sound card do you own?
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I got my HD 580 from a dude selling brand new ones on eBay for $180, shipped. For the headphone amp, I have a Headroom Total Airhead ($110, shipped), with an iPod lineout between the iPod and the headamp. My source is an 80 gig iPod Classic with most of my stuff ripped to Apple Lossless. Like I said before, overwhelmingly the application is music listening rather than gaming, so I haven't optimized for the gaming headphone application. The Total Airhead has a cousin called the Total Bithead that acts as a nice quality USB sound card. It costs more than the Airhead and it jettisons the ability to use an A/C adaptor (both the Airhead and Bithead are portable, using 4 AAA batteries for that purpose) in favor of the USB soundcard feature.
When I got my headamp, the first thing I did was a bunch of before-and-afters with my SR-60, since that's what my ears were used to. It did help the sound, with a noticeably enhanced (better separation, not just plain louder) bass. I also noticed a bit of a midrange clarity boost, as well. It also lowered the the small bit of hiss/noise you get from jacking directly into the ipod. Whether that would be worth the cost WRT to the SR-60 is a tough question. I can say that I'm very pleased with my HD 580/Total Airhead headphone/headamp combo--way worth the cost to my ears.
I've read that a very good sound card does a credible job at being a decent headamp--you might not need one if you are always jacked into the comp with your nice soundcard. If you don't do weird sound editing, its entirely possible that the Headroom Total Bithead is a good thing to research for your needs.