I'm having the same issue: Since the latest Windows 10 update 2004 the sound from Razer Surround Pro is crackling/distorted.
I'm using Razer Surround version 1.05.28 and Razer Synapse version 2.21.24.34
The Razer Surround Audio Controller has driver version 15.57.36.635
The Razer Surround Audio Controller enhances my Realtek High Definition Audio Speakers, driver version 6.0.1.8366
I tried re-installing both Synapse 2.0 as well as Razer Surround Pro several times.
I also tried fresh installs after cleaning up the registry, used DriverStore Explorer to remove the driver and re-install it etc but to no avail.
Eventually my only solution was to restore a previous image of my PC to revert from Windows 10 2004 back to 1909.
My system is now back to how it was before the update and Razer Surround Pro is working fine (on 1909).
For testing purposes I retried the update to Windows 10 version 2004 and was able to reproduce the issue.
I have also contacted Razer Support on this issue and they asked me to report this to Microsoft since it's occurring specifically after the 2004 update.