When I built a HagDac directly into a Transcendent Sound Grounded Grid pre-amp, I simply duplicated the +/- 8V DC power supply from the Chime. Has worked great for nearly four years now.
Mind you, I love my two Chimes. However, I wanted a slightly more sterile -- less 2nd harmonics -- tubed DAC for listening to harpsichord and some other types of music. Hence my wedding a HadDac to a GG with the GG +30dB gain mod.
I even have two PCBs left over which I used as carrier cards for the HagDac: they have the S/PDIF input, +/- 8V input, L & R outputs, plus circuitry for rolloff and phase switches and the bi-color PLL & RCV LEDs.
Separately, I built a PCB to provide ground isolation for two electrical S/PDIF inputs as well as two TOSLINK inputs. (Not becasue I like TOSLINK. Rather I wanted to see for myself how good/bad it is.) For USB input, I just used a HagUSB card. Finally, I hand wired a board to get the needed +/- 8V DC. I think I still have two of the signal handling PCBs around as well, but the PSU PCB was a one-off if I recall correctly.
Dan