A few more suggestions: if the amp is not going to be fully balanced, make sure to offer a 1/4" headphone jack. XLR jacks are not necessary unless the amp is truly balanced. In any case, most people do not have balanced headphone cables lying around. Also, adding too many features -- like speaker outs, DAC, remote -- may drive up the cost for features that most won't use. I have owned headphone amps that can double as preamps and low power integrateds and never use them for that purpose. Avoid making an amp that seems to be a potential "jack of all trades, master of none". Finally, Woo is in need of some competition in the $1200-$2500 range. Above that price, though, and the potential market thins out a lot and you will start competing with Eddie Current, which seems to operate on low margins and is well regarded.
Oh, one last request, create an amp that has some tube warmth. Singlepower sold a lot of amps before it imploded. Users loved them for a combination of midrange warmth and great dynamics. The remaining amp makers seem to adhere too closely to the straight wire with gain manifesto of amp design.