It is not the bluestacks itself that is fixing the issue but rather virtual box that is installed alongside.
I have installed just the virtualbox alone and started a windows machine, with the absolute bare minimum and razer surround seem to not produce any disruptive noises. it seems like a virtualization problem not sure yet were it has the roots.
Furthermore, seems like you don't even need to start the virtual machine to have the sound fixed,
I've set a win10 VM (in virtualbox) and allocated absurd low specs like 2MB disk and 4MB ram and started it, after this a pop-up is displayed to select the disk and at this point the sound works fine, but the VM is not running yet (would not run with 4mb anyway) So it seems that some services are started to prepare the VM and these are fixing the sound not running the VM itself.