If I’m reading it correctly (and apologies if I’m not, I’ve just woken up), shouldn’t your condition block be…
condition:
- condition: state
entity_id: sun.sun
state: below_horizon
- condition: or
conditions:
- condition: state
entity_id: media_player.sony_XXXX
state: 'on'
- condition: state
entity_id: media_player.panasonic_XXXX
state: 'on'
(which says the sun must be below the horizon, and either of the media players is on)