Using a different test tone I'm now measuring 1.6 V AC at both plugs with the 5 V output selected. Closer to 1.3 V with 4 V output selected. Pixel 9 phone wired USB to DAC, volume on phone max, DAC set to pre with volume 100% or DAC only both had exact same measurements. Not finding any additional info with quick web searches of what other settings, phone or DAC, could be impeding the output voltage. Shouldn't the 4V and 5V put the same 2 V out we're looking for or shouldn't they be up at the 4 and 5 V? The only settings in the DAC are PCM filter, 4/5V output, bandwidth. All of which were changed and tested without getting to 2V. Any way it is cable related? DAC power supply? Or pretty sure it's the DAC? Anything top of mind I could check in the DAC settings? Is it the phone? All tests have been through pixel android USB to USB DAC.
I am finding a post about Android USB output and an app to bypass that and allow the DAC to figure it all out, it's called UAPP pro. Maybe the phone is the culprit? Almost putting a limiter on the USB media transfer?