Problem with 2204 build

[JayB]

Check your buss ground you got there. Make sure it's properly grounded.

[Coolhat]

Success at last! I double-checked the grounding, measured all the resistors and caps again, but in the end the culprit was the gain pot. I replaced it with a fresh new one and now the voltages are spot on and the hum is gone. Big thanks to everone that helped!