From what I have seen the people that are playing with "balanced" headphone output (which seems to be more concerned with supplying separate signal cold rails for each channel rather than balancing the output signal with respect to ground) are using a full sized 3 pin XLR connector for each channel. So that is what we are using. Not sure that I grasp the second question properly, but the single ended and balanced outputs are all switched from the output transformer, so there won't be a need for any additional transformers.
From what I understand......
16 ohms 1.8 volts 112mA
32 ohms 2.5 volts 80mA
64 ohms 3.6 volts 56mA
128 ohms 5.0 volts 40mA
Want to give a status update to those who have pre-ordered. We haven't forgotten about you! As happens sometimes the process of getting the parts together is taking a little longer than expected. Our laser cutter has been swamped and it took a while for him to get us a quote so we could order the chassis plates. They are now in the production queue as are the transformers. Should be a couple/three weeks and we will have some kits to ship.