Precisely Adjust Volume Levels on your Mac
You can precisely adjust the volume levels on a Mac by holding down the Shift+Option keys while pressing the Volume Up/Down keys. This lets you adjust the sound level by 1/4 of each notch (as opposed to a full notch).
This is perfect if you like to precisely adjust the audio level of speakers, though it’s used best with external speakers which tend to play either too soft or too loud. Easily the best way to find the best volume for you.