[malvinas2]

I am using Kodi 16.1 with Windows 8.1 Pro 64-bit, running on an Intel NUC i3.

I observed that the volume when using Kodi is quite quiet ;-)

In the Volume Mixer all volume levels are set to maximum, the overall system volume as well as the application volume for Kodi.
Within Kodi the volume is set to 70 and the volume level sounds 'normal' to me.

But when I terminate Kodi and start another windows application like DVBViewer or whatever, the connected television set starts 'screaming', so I have to lower manually the volume of the television set a lot.
Or when I change the HDMI source from my HTPC to the Nintendo Wii U of my son, the television set also starts screaming.

Within DvBViewer or the Nintendo Wii U I could set the volume level that high, that people at the other end of the town would complain. But it is impossible to reach this volume level within Kodi.....

Why is there such a difference in volume levels (I am using default audio options of Kodi) ?

[PatK]

You might set Kodi's volume at 100% and then there is the volume amplification setting; both in the audio OSD while playing a video; and you can set it globally. In general, HDMI the audio component is handled by an external device, and depending on the type of encode (dolby etc) there is going to be post processing of the signal, usually with quality of the origins and depending 5.1, 7.1 DTS, etc... the signal will get post digital processing by that equipment which may limit the audio wave form. While most PC and game sources will be analog and the loudness reference will be much higher as the manufacturer builds for worst case scenario and swamps amplifiers.

My suggestion is to limit the analog amp,or tie it up with and boost the digital with an AVR. A side note is that your HDMI hardware source output (graphic card) handles the audio levels, there may be a hidden tweak in your card, refer to the manufacture for this.