I'm on my second Pico Dac/Amp - so I obviously like that piece of kit. I can't seem to justify getting rid of the Pico Slim, at least yet - I haven't found a better amp for sensitive iem's. My iem head-time has dropped way, way off, though. I just don't have time to have what are effectively custom fit ear plugs that play music stuffed in my ears. At work, headphones are much more convenient. I rarely listen at home any more it is either the speaker rig or my daughter's cartoons.... The iem's are reduced to travel use, and I don't travel all that much. As well as the Mad Dogs isolate, I could travel with them, though they are kinda big.
A couple more notes on the Picos - I finally gave a bit of time to the big Pico with my touch 4G (ALAC files). It is a bit better than the slim, maybe. Overall, the Pico Slim does a fine job with the Mad Dogs, though. The big pico is not enough better to need to carry it with the touch for a portable mad-dog rig. That said, the Pico used as a dac / amp from the laptop with lossless files is MUCH better, so the Pico still fills the main need I bought it for. So would a DacPort, though, since it seems the Mad Dogs do not benefit so much from the added power with the touch 4G.