XPS15 Dual Monitors - 2nd only mirroring 1st

@mike010101  You've cabled and configured the displays properly, so the only potential issue I can see in your setup is that adapter you have, which I hadn't seen before.  The fact that it also incorporates an HDMI output (which I realize you're not using) means it would need to incorporate an active signal converter chip (since USB-C/TB3 video output uses DisplayPort natively) and generally "manage" the signal rather than simply passing it through.  And I'm wondering if that adapter doesn't pass through DisplayPort MST, which is required for daisy chaining.  Also note that if you're using that adapter for power passthrough, the specs say it can only pass through 90W.  The XPS 15 9560 is designed for a 130W power source, so if it's only receiving 90W as a result of that adapter, it will respond by reducing battery charging speed and possibly throttling performance.

I would suggest connecting to Display #1 using a simple USB-C to DisplayPort cable and then plugging the system's 130W power supply into the barrel connector dedicated to that purpose.  If the barrel connector on your system doesn't work, then the only way to run dual 1080p displays and get a full 130W to the system all over the USB-C/TB3 port is to use a dock like the Dell WD19 (or the WD19TB, which would allow even higher-end display setups).

Appreciate the reply! I think you may be right about the adapter. The specifications state the max output is 4K, so I was led to believe it would be able to support daisy-chained signals. I've ordered a USB-C/DP from Amazon...hoping it'll work.

I'm not using the power passthrough on the adapter to charge my laptop; the charger is connected to the laptop normally (I don't see a way to connect my charger to to the adapter's USB-C port...I assume it's for the newer laptop models that use a USB-C charger)?

@mike010101  Happy to help!  Please do report back as to how this goes. in terms of the power passthrough, the XPS 15 9560 supports drawing power through its traditional barrel-style connector and also through USB-C.  Although I believe that if you want to send 130W over USB-C with that system, you have to do it through a Dell dock like the TB16 240W or WD19/WD19TB 180W.  Dell does make a 130W USB-C power adapter, but it wasn’t introduced until the XPS 15 9575 was created, because that system requires 130W but doesn’t have a barrel style connector. (And it’s also used now on the XPS 15 9500 and XPS 17 9700.) Anyway, I seem to remember reading that some users tested that 130W USB-C charger on older XPS 15s and found that even though those older models will draw 130W over USB-C/TB3 from those Dell docks, they would NOT do so from that power adapter that was created more recently. I’m not sure why Dell couldn’t (or didn’t?) make that 130W adapter backward compatible with older XPS 15 systems, especially given that the WD19 dock family was introduced even more recently than that power adapter, and those docks CAN push 130W to those older XPS 15 models. But that seems to be the finding of people who tested it.

So on further reflection, I guess the power passthrough capability of that adapter is useless for you, because the only power sources that can push 130W that way are Dell docks, and if you’re connected to a Dell dock, you wouldn’t need that adapter — on top of the fact that the adapter seems to limit you to 90W anyway, independently of any other restrictions. Sorry for the confusion on that front!

No worries and yep I'll report back tomorrow when I get the adapter!

@mike010101  Excellent!  Thanks for reporting back, and glad to hear you're all set.