I also want to see implemented that the iDSD micro will have a very powerful internal battery which will either be providing a high current to power a huge range of headphones or also be having a battery run time of 20 hours plus.
Based on the previous feedback it seems that unit should have the gain switch (which I think is essential if a headphone amp is part of the design) and the the 3D function (and Bass Boost?) implemented .
Here is my concern, I would rather have the DAC side of the design prioritized (Filters, Up-Sampling of PCM files, Phase Invert Switch) but I also see potential for the headphone amp features being implemented at the same time. My suggestion would be to put more options at the bottom of the unit. The front of the unit should have 2 switches, 3D and Digital filter for example (things that need to be changed quit often or options that are fun to play around with while listening to music). All the other functions could be neatly placed on the bottom of the unit (like the DIP switches in the iPhono), including Gain, Phase Invert and even functions like running the unit from USB power or the battery.