QAudioOutput::SetVolume()

Hi,
it seems that on some systems, volume over 0.5 doesn't work.
I've this issue too on QT5.0.2 and Win7 x64.

If I set my volume to a value >0.5, it automatically goes down to 0.5.
I have the same issue on the tutorial exemple (Audio Output Exemple).

I only have this issue with Qt related applications and everything is okay with other ones.

Thanks.