Following the advice from Dell Support, and since the audio except from that startup sound glitch was working flawlessly, I uninstalled the current Audio driver and installed the previous version. As I expected the problem was resolved, as it was attributable to the latest (6.0.9247.1) driver. But there was more... after rebooting a couple of times with the older driver (to check that Windows startup sound works), Microsoft Windows Update offered to update the older driver to the version I had installed from Dell site and gave me the problem ( 6.0.9247.1). As I had already a system image, I let it update to the new driver.... and miraculously the problem didn't come back.Checking the files I had installed after the Windows Update with the ones contained in the Dell Audio Driver, there are a few differences in the “.cat” files of the driver! The Dell ones were significantly larger compared to the ones installed by Windows Update. Apparently, Dell customizes the driver, to such extent that creates some problems.I did mention it to the Dell Support guys, who noted it! Hopefully the next Dell update won’t have the same problem.In any case the problem, was a driver problem and it was resolved by reinstalling the previous version of the Dell provided driver. Now, for me (at least until the next clean install) Dell audio drivers are not much of a help (since they are updated by Dell in a very slow pace).After the initial Audio driver installation with the Dell provided package, I usually update all the Audio driver components from the Windows Update Catalog, by downloading the Basic driver, the required Software components and the latest Maxx Audio Component from there and apply them to the existing installation.   Hope this helps someone with a similar problem!  
Hi everybody, On a brand-new Precision 3560 i7-1165G7 (Nov. 2021), which I clean-installed with Windows 10 21H2 and installed all the latest drivers  from the Dell Support site, I have enabled the Windows startup sound. Fast startup and Hibernation have been disabled. When I reboot the laptop, the Windows startup sound starts at logon, but it cuts out after playing the first 2-3 seconds. That happens intermittently. The Audio driver is the Realtek 6.0.9247.1 (complete package installation from Dell) I would attribute it to a Realtek sound driver bug (and wait for the next sound driver update from Dell)…but maybe someone else might have a better idea or solution to that. Thanks a lot. Dimitri
Precision 3560 - WIndows 10 Startup sound cut out