Hi I have developed a custom sAPO for applying custom audio effects for Windows 8/Windows 7. Now I want to install this sAPO in win 7 and 8 system? Could please let me know steps to install the sAPO. As I read in some documents and forums, sAPO should be part of audio driver. I don't have any audio driver. Right now I am updating system speaker sysfx.ini file (HDAUDIO). I have used custom sAPO gfx and lfx GUIDS in this inf file and created self signed certificate to install my SWAPAPO.dll. Questions: 1. Is it necessery to write a audio driver? Is it specific to a particular audio device? 2. Do I need to virtual audio driver? How? any links. 3. I want to install this custom sAPO for all devices in my system. So what is the installation procedure. please help me out here. 4. Is it possible to install the sAPO in windows 8 and 8.1? Thanks NMath