I've been sitting and dialing in some decent amp overdrive/distortion tones with my better Sennheiser HD6 phones (which are more of a reference type headphone). The results have been pretty good so far, but a lot of that depends on the amp model. The Placater Dirty (for rock tones) and the Cali Texas Ch.2 (for blues tones) seem to agree with the phones pretty well. Of course, most all of the clean amp tones sound pretty good through phones without much tweaking. I had a conversation with a sales engineer at Sweetwater who recommended trying the AKG K240S semi-open back headphones. I considered buying the MKII version of these which are $100 more, but I ordered the original series to start with. They are supposedly the same phones except for a few cosmetic and feature changes. Same transducers and frequency ranges though. I'll chime back in later on and let you know how they work out unless someone out there is already using these.. in that case I would like to know how they work with the POD Go.