Thanks to Noel Hibbard’s excellent suggestion, I can now control rf2’s (and rfactor’s) output volume using hotkeys assigned to the “AutoHotKey” command utility. Volume control is realized by using “nircmd.exe“, another fine freeware tool which can do much more than just control app volumes (google will find both tools quite easily for you).

(c) VirturalR.net

In the following setup as copied from my AutoHotKey’s default setup file, Ctrl-PageUp / PageDown increases / decreases rfactor(2)’s sound output, while ALT-F3 mutes vlc.exe (or toggles the mute, rather) as I often watch real life racing on TV with half an eye on the 2nd monitor while beta testing rf2 which is very handy for those nasty ad breaks:

^PgUp::
 Run, nircmd.exe changeappvolume rFactor2.exe 0.05,,Hide
 Run, nircmd.exe changeappvolume rFactor.exe 0.05,,Hide
Return

^PgDn::
 Run, nircmd.exe changeappvolume rFactor2.exe -0.05,,Hide
 Run, nircmd.exe changeappvolume rFactor.exe -0.05,,Hide

Return

^!PgUp::
 Run, nircmd.exe changeappvolume ts3client_win64.exe 0.05,,Hide
Return

^!PgDn::
 Run, nircmd.exe changeappvolume ts3client_win64.exe -0.05,,Hide
Return

^!F3::
 Run, nircmd.exe mutesysvolume 2 ,, Hide
Return

!F3::
 Run, nircmd.exe muteappvolume vlc.exe 2 ,, Hide

Return

Note that you’re not limited to using the keyboard, you might just as well use buttons on your wheel or shifter (the autohotkey documentation has all the details).

I hope you find this info useful and enjoy a more or less “noise-free” racing experience.