I have my Node 2i connected to my SGCD two ways: 1. Digital Coax. 2. RCA analogue.
Switching between the two inputs to hear each DAC, the volume of the Digital Coax is significantly louder.
I called PS Audio and they didn’t understand this or why it was happening.
Anyone else hearing this?
Same here. My CD player is connected to my GCD via Coax and RCA analogue simultaneously and Coax is clearly louder. Kinda make it difficult to A/B between the on board DAC and the GCD’s DAC
Agree, it also makes volume “1” kinda loud sometimes.
This is to be expected. Ideally, RCA out of the node will be line level, just like a CD player. Voltage may vary a bit. The digital out will be completely different. The level of the processed signal by the GDAC’s DAC will be higher. You are attenuating the signal in both cases, and the signals going into the GDAC’s pre section are inherently different.
In order to do the comparison, you’d need to send the GDAC the line level signal from both systems. Which would need two GDACs. I’d be more than happy to get you another one! 
I have the same thing when I switch from CD player (optic cable) to USB drive from PC (Audirvana). I assume it is normal. I’ve had it happen in most systems I’ve had.
I do this with my Anthem STR Integrated and there is zero volume difference. So it’s definitely in the way the PS Audio processes the signals.