If possible and if resources are available, would be nice if there's some faction specific background music that plays and fades in/out based on the current situation of the match.
So for example there's generic battle music during the match, but if one side/player begins "winning" decisively their faction's theme music begins playing (globally). Would add a lot of flavor to the current factions with minimal work.
Also would be nice if the state of a ship is reflected when you select it with small auditory cues.
So for example, when you select a ship and it plays the audio bark, you could have things like sirens blaring in the background if the ship is damaged, shooting/fighting audio if the ship has recently taken a boarding action, muffled loud explosions if the ship takes damage as you select it or it fires as you select it.