Like Apple, HTC has decided to ditch the headphone jack. It's replaced by a USB-C port (which it also uses for charging).
Whether it's the future or not, it's hard to not find it annoying right now. Even if an adapter is included in the box, it's rarely there when you need it.
A pair of USB-C in-ears is included, with active noise cancellation. They're better than a lot of bundled buds, but have a tendency to be a little bass-heavy for our tastes, and the noise-cancelling is subtle at best.
If you use them, you'll be prompted to set up a sound profile, which is calibrated to your ears. It's a quick process – the U11 fires a test-tone and automatically adjusts the sound based on what it receives back.
You can then listen to the before and after, and choose which you prefer.
The adjusted sound is cleaner and louder, but sounds processed, and the added bite it gives to the treble verges on harsh.
Listen through better headphones using the adapter, and the sound is much improved. It's well balanced and plentifully detailed - but could be more dynamic.
As it is, it's a touch laid-back – an easy listen, but not the most engaging. The amp in the adapter struggles to drive less sensitive headphones, and the volume doesn't go as loud as we'd like.