I was about to post another Q about amp and DAC...specifically, how to recognize a good product, without relying on reviews and subjective listening abilities of different people...
And I found all my questions answered by the man himself...NwAvguy.
Thanks and respect...I hope he's still alive.
Links to articles:
http://nwavguy.blogspot.co.uk/2011/08/o2-details.html#resources
http://nwavguy.blogspot.co.uk/2011/07/o2-headphone-amp.html
http://nwavguy.blogspot.co.uk/2011/07/o2-design-process.html