During installation of SFX, an audio engine is registered on the computer that'll be used to connect to an ASIO sound card. If there is a failure in registering the audio engine, sound will not work on the computer. The indication that the audio engine is not registered will be logged in the SFXv6Log.txt file located in Documents\SFX6 with a line similar to this: [27/06/2020 3:01:19 PM] EXC : Could not load file or assembly 'Audio.Engine.Interface, Version=2.0.6563.24196, Culture=neutral, PublicKeyToken=ce008ae731e2b29e' or one of its dependencies. The system cannot find the file specified. at StageResearch.Windows.SFX6.Engine.#ye(Object #G, ListChangedEventArgs #H) at StageResearch.Windows.SFX6.Engine.#we() at StageResearch.Windows.SFX6.frmMainFrame.#Gk() at StageResearch.Windows.SFX6.frmMainFrame.#Bk(String #ee) To resolve, follow these steps: 1) First try to install SFX in administrator mode. If that fails do the following: 1) Run an CMD Prompt in Administration mode. (Right click on the CMD icon and then Run As Administrator) 2) Navigate to the SFX6 folder cd "\Program Files (x86)\Stage Research\SFX6" 3) Register the audio engine, type in: c:\windows\system32\regsvr32 Audio.Engine.Worker.dll A dialog box should pop up giving you an indication if the registration was successful.