Normally you connect the DAC-9 RCA outputs to HPA-9, and then HPA-9 RCA outputs to STA-9.
You can listen from your speakers or headphones by fixing HPA-9 volume and use DAC-9 to adjust.
The issue here is when using the turntable as source and still want to use the DAC-9 remote volume control.
This connection should work but I need to check with engineering if it will create ground loop noise:
- Connect DAC-9 XLR outputs to STA-9
- connect DAC-9 RCA outputs to HPA-9
----> connect HPA-9 RCA outputs to DAC-9 RCA inputs
So when source is phono input, you would fix HPA-9 volume (there is memory retention for each input) and set DAC-9 input select to analog.