According to this review: https://www.windowscentral.com/dell-xps-27-review

the MaxxAudio software controls the speakers, so perhaps you are looking in the wrong place.

Well it might well be but under the MaxxAudio software (which btw is provided with the unit) I have no settings to enable/disable 5.1. I have just a "Stereo to Surround" greyed out.

I know you said you have the latest drivers, just make sure the Realtek High Definition Audio driver is loaded. The latest version appears to be Version 6.0.1.8166, A05. I am not sure if Windows update may install a different version.

I looked at the sales page for that system and I could not find any information regarding the sound reproduction.  I see it has two speaker modules which probably contain the speakers you reference.   But I did not see any claim the system was a 5.1 system.

The system only has the Realtek sound drivers, which probably include the Waves software.  You might look in the hidden icons on the taskbar to see if there is some audio icon you could open and sometimes you have to right click those to open the settings.

You might also check the control panel to see if some audio interface is hiding there.  The system may be more like a 2.1 system but not sure.  If it is, you may find a subwoofer level setting if you check the Settings-System-Sound and look for the link on the upper right for the Sound Control panel.  If you select the speakers, you may be able to use the Configure or Properties to change some settings.

During one of microsofts many self destruct feature updates the OEM drivers likely got nerfed.   Do all your updates then uninstall the audio driver and reboot.  Then Re install the audio driver making sure to run as administrator.  You say 6 speakers but I only see 2.

http://downloads.dell.com/FOLDER04355339M/1/Realtek-High-Definition-Audio-Driver_68WY3_WIN_6.0.1.8166_A05.EXE

DELL XPS 27 7760

http://downloads.dell.com/published/pages/xps-27-7760-aio.html

I have uninstalled/reinstalled the realtek audio drivers.

I think the issue here is: my speakers are just "speakers" I see nowhere in the device manager anything I can set to make this working 5/6/7.1

Googling the question I can see Realtek has a utility for this but I don't see this installed on my system nor it's provided to me via the download area of the drivers for this system.

I linked the specific Driver

http://downloads.dell.com/FOLDER04355339M/1/Realtek-High-Definition-Audio-Driver_68WY3_WIN_6.0.1.816...

Thanks that fixed the tray icon but the system still thinks it's on a stereo

I have not found anywhere in my research that the XPS 27 7760 supports 5.1 surround sound. Do you have any documentation that this system has this capability? It seems to me that the lack of front L/R and rear L/R surround ports is an indication that surround sound is not possible.

You might be right.... but I mean, what else would you do with 10 (ten!) build in speakers?

6 are under the screen facing the user, 4 at the back.

Are we saying that 5 speakers play the left channel and 5 the right one? :-s

It seems to me that true surround sound should physically surround the individual listening and not just the computer itself. I think the number of speakers is used to cover various frequency ranges, each individual speaker is optimized for a frequency band.