I'm modding an Adcom CD player for a member here, installing a pair of Colin's I/V boards (player is balanced), and am debating on how and where to connect ground on these to the main board and power. These boards have on-board shunt regulators, so I am tapping power from the main filter caps right after the rectifiers for the 2 +/-15V power supplies for the analog section on the main board. AFAIK, it is usually not a good idea to connect more than 1 ground per board. The options I see are:
Ground the boards through the power connector Ground the input of the boards Ground the output of the boards
Currently, I am leaning towards #1, thinking that noise from the shunt regs, etc. should feed back to the ground plane near the PSU instead of being dumped into the ground plane near the DACs. Ground plane seems to be common between the sections. The one that Colin did (same player) used #2.
The stock analog stage is completely depopulated, other than the muting relays. From the schematics, it does not appear that anything else uses the +/-15V supplies.
Thanks for any thoughts.