Having the volume control in the same position only works if the sources you are using have the same output voltage. Have you checked that? Higher voltage means more volume at the same position of your pot.
Yes, output voltages are the same (as reported by manufacturers specs).
unless your sources are level matched (exact same output voltage), you are not level matched anyway. Considering you are switching between RCA and XLR inputs, it is unlikely that your sources are level matched.
Did not switch between RCA / XLR for testing components A/B. I only used that example because I have the Yggy hooked to my am via *both* XLR and RCA. So I did switch to compare XLR/RCA from the same device. Nevertheless, my thread question regarding potential amp impact still applies.