A little more digging has revealed the model in the link above was a simple rebadge of a chinese jobby and then doubled in price. Not made or desinged in the UK as claimed and using basic generic drivers.
I would suspect the new "carboncans" are more of the same. Maybe a search on Alibaba would reveal the original?
Well, if the material is decent and they're put together well, then I can forgive a little shortness on the sound. The bold ad showing the design and materials was exciting. Just recently I discovered that Brunton, the compass company, moved their China production back to Wyoming USA, so I bought their $300 transit. Very uber-cool bit of kit, but completely useless in the urban jungle of course. Now seriously, looking at the tech parts inside, I can't believe that all of those parts aren't sourced from China and then assembled by Eskimos** in Wyoming. The idea of building from scratch is fantastic, but just that - a fantasy. Imagine if we could create a factory to build valves for stereo amps etc., and pull together some retired folks or slackers to work there. Now that's a concept with a future.
**It's too cold in Wyoming for most Anglo people - 90 below f. on a good day.
So anyway I've followed up and - several months after this item has been released, there are no reviews anywhere except mine. The only other review is on a website they also own. I visited their Facebook page, which has only about one user post every other month. My two comments are unanswered. There are long gaps on their Facebook page - one gap is 6 months between posts. It gets more interesting - the Carboncans headphone was created after a Kickstarter project apparently.