|Sounds like you should get the Amp first and see how that helps your DT770s. Then, decide on a headphone afterwards (with the Amp already out of the way).|
I'm going for the Little dot MK2. Seems like a good entry level, and I hear that the tube amps are better for spacial effects and soundstage, as well as enhancing the "warm" feel. Anyone have experience with this amp and gaming?