I am pleased to share excellent news on this subject.
I bought my XPS 13 (9333) in November 2014 and have been in constant communication with Dell. Today I have received a new XPS 13 and the noise issue is gone!
The problem on on the 9333 variant of XPS13 was related to interference of the cable supplying the right speaker.
Dell have now replaced the 9333 variant with 9343 version. It's an entirely different beast and I have only just received BUT the noise issue is definitely no more.
- 200g lighter
- slightly smaller
- much higher resolution (now 3200 x 1800) + much brighter
FYI: I am a Linux user and this device is shipped with Ubuntu again.
Am very happy; will now test the full product and report back if I find any issues.
My advice? Get yourself an upgrade to this new model ASAP 🙂