Hello,
Here some pictures of my M3 headphone amp. I have used the normal parts from the BOM on the amb website. The headphone amp sounds great with my HD580 ! I have used an amplification of 5 (4k resistor) which is plenty for any PC and CD source with my HD580 to have a good range for the volume level pot. I have placed the transformer (I bought a normal pcb transformer from mouse instead of the fancy toroidal pcb version from digikey) in an old walwart housing from an old zip drive, because when it was next to the headphone amp pcb I had a little hum.
Before the amp was in a housing it had a little noise and hum, but now in his housing it is dead silent even with open volume (with nothing connected to the amp rca's). If you connect a dac you will hear the noise from the dac a little bit (NOS DAC).
Have fun,
Edwin