I have just bought a K95 Platinum keyboard and Scimitar mouse and get the same pesky disconnect sound when launching iCUE. I have no other issues. I ran the following PowerShell command to compare devices before and after opening.
Get-PnpDevice | Format-Table -AutoSize > devices.log
It looks like the software is connecting/disconnecting some virtual devices. Devices that went from status "Unknown" to "OK":
HID-compliant mouse - HID\VIRTUALDEVICE&10&COL04\2&1F1CA0F9&0&0003
HID-compliant consumer control device - HID\VIRTUALDEVICE&10&COL05\2&1F1CA0F9&0&0004
HID-compliant mouse - HID\VIRTUALDEVICE&10&COL01\2&1F1CA0F9&0&0000
HID Keyboard Device - HID\VIRTUALDEVICE&10&COL02\2&1F1CA0F9&0&0001
Devices that went from from status "OK" to "Unknown":
HID Keyboard Device - HID\VIRTUALDEVICE&10\2&1F1CA0F9&0&0000
Maybe this is just a red herring, but could that last keyboard device be the cause of the phantom disconnect sound? I also get some errors about devices in the application logs on startup (see attached), but I haven't been able to spot any IDs matching those above. 2019-04-25T18-03-17.log