TDA7492P Volts VS. Volume

Does the input voltage of the module determines the output sound volume (or gain if you like)? In the specification of the amplifier chip, I found characteristics telling that, 2 times volts will provide 2 times amplification. But in real time I did not have noticed any change.

Audio: Cold Funk - Funkorama - Kevin MacLeod ... https://www.youtube.com/watch?v=mDEtyuHuG4s