Latitude D630 Windows 10 (32bit) audio distortion

After (many) years of solid service with XP, Win7 and now Win10 without issues on audio playback some update in recent months has broken the audio output on my D630.

The problem is a somewhat regular buzzing reverteration repeating at about 1 per-second.

The fault occurs with build-in speaker and external speaker and with Windows Media Player and Skype.

Device manager reveals that the driver for the HD audio speakers is Microsoft 18/03/19 v10.0.18362.1

The event log states the driver was "migrated" 7th March 2020.

Update drivers states I this is the best available driver!

Can anyone point me at an audio driver that works (as it has done for about a decade)?!