I just got the XPS studio 16 (it came last week) and so far it's working great (the laptop), but I noticed the exact same thing. I've only left it plugged in atm long enough to recharge the battery while using it, and the AC brick is scorching hot. It doesnt' seem to be getting any hotter though, so I'm wondering if this is normal since the brick is so thin? It was shocking enough touching it though to get me to come online to check if anyone has similiar stories.
yes! here's a similar story: I got my Studio 17 four days ago and noticed that the brick portion of the included 90W adapter runs quite hot (about 40-45 C) after being powered on for no more than 15-20 minutes.
with the exception of a slightly warm touchpad area (presumably where the AC Adapter not charging my Acer battery hard drive is), the rest of the notebook stays very cool.
(but having said that, I did buy a notebook cooler to elevate and cool the beast).
I can pick up the adapter and hold it in my hands without burning myself (it's not as hot as a freshly baked hot potato) but yesterday,
shortly before powering it off for the night, for the first time, I heard that "low cracking noise" that other people here have also mentioned.
i ended up talking to Dell about the issue and they sent me a replacement power brick. I'm honestly still using the original brick with cord and haven't tested the new one. I'm pretty sure that it's working as intended anyway but just running hot on a heavy work load. Other than that, it's been fine. Not sure where to go from here but I think that it'll be fine.