The schematic shows both the headphone and speaker outputs being referenced to ground. However, the TRS socket I got is 3-way switching (and the 0ohm resistors are on the speaker side), so the headphone output is not referenced to ground.
My speaker and headphone outputs are on front and back panels. I assume it would be OK to make the ground reference at OT1 and OT2 (so that the headphone output is also referenced to ground)?
Thanks,
Jeff.