Welcome to the club psone. Do you have the 600 ohm DT880? I too have read they're an excellent pairing with the MK IV so I'm sure you'll enjoy it. I brought the MK IV SE to pair with the HD 650 as my first serious setup, but I hope to invest in a few additional headphones in the future, and the 880 600 ohm is on my list.
The DAC_I (or any DAC) is a very worthwhile investment to get the best out of your headphone and amp, plus is looks great with the MK IV stacked on top of it . My MK IV SE is currently on its way back from being repaired, but as soon as it's back in my possession I'll be posting some pictures (though I'm not sure I can match tiramisu515's excellent shots) and more comprehensive impressions - and enjoying its great sound of course.
Edited by jr41 - 11/17/10 at 1:21am