I have XPS 13 9343 and I haven't noticed the coil whine. Which model do you have? Do I not notice it because it's not there or because of ambient noise/poor hearing?
9350 with i7. Just keep your ear near the keyboard. With a bad combination of video drivers the whine is super loud. People in video conferences were asking about the sound (thought it's HDD but I've got SSD). If you don't hear anything then congratulations! Maybe previous models did not have this issue? Do you have Thunderbolt port? If so I'd check 9343...
What OS are you running? My "coil whine" was significantly quieter when running Windows. Running the preinstalled Ubuntu the whine was like 200% louder.
