I've installed an older version of the driver, which has brought back the MaxxAudio thing. I do love wasting my time off fixing issues on my new thousand pound machine in a slapdash manner. Is the audio on a computer particularly difficult to get right? 

Just so you know, the Windows Upgrade build did not remove the Waves utility from any of my systems.

I believe one of the reasons the Windows cumulative update came out on the 14th was because the FCU upgrade process was replacing some drivers with Windows 10 basic drivers... but I could have misunderstood.

I still had the realtek driver installed without any options to revert to a previous version through the sound manager. The version installed was more recent that the one provided on the Dell website, which I have installed now. The MaxxAudio program had completely disappeared from my system, however.

Since the Windows update was installed I get an intermittent message at startup stating that Maxx Audio was removed, however, it's still there?  Makes no sense......I have an 2017 XPS 15