1) i've read that BNC connectors are far superior to RCA digital inputs is this true and if so why not include it in your dac's
2) what about a mono and upgradable power supply like the Cyrus Audio's psx-r power supply or naims many options
3) higher headphone current level to account for AKG top end models
4) http://diyaudioprojects.com/Solid/DIY-Lightspeed-Passive-Attenuator/
The electrical differences
The electrical differences between BNC and RCA connectors are negligible when used with the DAC1. We used to use BNC connectors exclusively, as seen on the original DAC1 and the DAC1 USB, because the looking mechanism made them more suitable for professional applications. However, more and more professional digital sources do not use BNC, so we decided that it was no longer necessary.
My question is... why wouldn't Cyrus or Naim use the best power supply in the first place. That is our approach.
Our headphone amplifier should be able to deliver more then enough current for any headphone model. If you find it is lacking, check the gain jumpers, as the default is the -10 dB setting. Consult your manual.
Best,
Elias