You should leave Volume Leveling enabled, but not Adaptive Volume, if you don't want to touch the volume control on your receiver.
Adaptive Volume makes audio playback louder. (volume level changes depending on the content)
Volume Leveling makes the volume at a consistent level across all media. (as much as possible)
Enabling both features will keep the volume even across the current playlist, but the volume level will change as the playlist does.
Volume Leveling may not be 100% effective with videos if you are downmixing (e.g. 5.1 audio output as stereo) or if the audio track has a lot of dynamic range, as it currently has a fixed headroom of 23dB.
If audio (music) has not been analyzed and Volume Leveling is enabled, the tracks will be played back at -10 dB.
If video has not been analyzed, volume level will not be changed. (0 dB)
If you plan on using either of these features, it's best to let MC analyze everything in your library.