I own the Grado SR60i and I currently have them running some 320kbps MP3s out of an Asus Xonar U3, which I have plugged into my laptop. I am going to be doing some nice mods to my Grado, and I was wondering if I might benefit from a better source. For the DAC + AMP, I don't really want to spend more than $100, I have more money, but I don't see the point in spending more money on the source than on the headphones... I haven't done any DIY DACs or AMPs before, however if it has good value return, I am willing to give it a go because I have all the tools required. Cheers!