Distorted sound when joining a phone call is due to the custom driver, and uninstalling it should fix the issue.  

Note: Once uninstalled, you can use other functions except Equalizer on Logi Tune.

Please follow the following steps to uninstall the driver:

• Open the “Run” dialog box by pressing Windows + R
• Type devmgmt.msc
  

• Click OK.
• Scroll down to Sound, video and game controllers > Select the custom driver for Logi Tune on Desktop (For example, Zone Wired) > Right click and select Uninstall device.