Noise in SACD through HDMI

I am at my wits end trying to figure out a noise issue in my system and am looking for new ideas to try.

Sources: Oppo BDP-93, Panasonic DP-UB820

AVR: Pioneer Elite VSX-82TSX

Problem: the Oppo is connected via HDMI and 5.1 analog input to the Pioneer. I’m getting a slight hum through both connections but less through the analog. The Pioneer is connected via HDMI and dead quiet. When I switch them, the noise follows the Oppo, no matter which HDMI input is used on the Pioneer. But I’ve tried two other SACD players (both Sonys) and they both have the same noise issue. That leads me to think that there’s some incompatibility between SACD players and my Pioneer AVR through HDMI.

Does anyone have a suggestion what else I might try to solve the noise issue that’s only present with the Oppo and not with the Panasonic? Any ideas would be appreciated!