It's not the keyboard. It's the software. If you're using Analog Lab 2 then it depends on the preset that the author used. Some are louder than others. If you're using the Grand Piano D, you could try increasing the volume on your computer. The other thing you can do is to use the volume control on the keyboard which sends a midi signal to the software. If the software's volume control is linked to the control on the keyboard, it should respond.