RE: Latest Version of Dell Audio is missing "Show Meters" button. (Windows 10, Dell XPS 8700)
Since you did the update to 10, it may not have updated the Intel chipset driver. Did you look for newer Windows 10 Intel Lynx Point (Z87) chipset driver on the Intel site? Assumed you tested the Windows 10 R2.79 driver here? The XPS 8900 uses the same sound card. You could try to install it. I am not sure if it will actually know the system model when installing but worth testing.
Version 18.104.22.16841, A00
Social Media Support
Run the PC pre-Windows diagnostics
Where do I find my Dell PC Service Tag or Express service code?
Out of Warranty Support