HEDD HEDDphone Two

These are by far the most expensive headphones I have ever bought, the necessity coming from the fact that at the moment most of my work is on location, far from my studio and monitors.
The HEDDphone Two are a fantastic tool for mixing and mastering, they're not designed to please the inner audiophile in us but to make the engineer work hard to get the best possible balance. They sort of make you realise how good they are not while you're using them but when you switch to a lesser pair of headphones.
The main caveat is that the sort of amp that comes with audio interfaces will not provide the HEDDphone Two with enough power to make them perform at their best.
My interfaces are a Metric Halo ULN-8, UA Apollo x4 Gen2 and the Apogee Duet 3. The Metric gets close but still not good enough, the other two make the HP Two sound audibly devoid of dynamics .
HEDD specify 1W as being optimal, going for more is a good idea. I'm using a not too expensive (relatively) Topping L70, which from the balanced out gives up to 6W and extrudes wonderful dynamics from these headphones. Yes, it's an extra box to carry around but it's worth it.
In terms of comfort they are pretty good as far as 550g headphones can be. There is more clamping force even when you adjust them for minimal pressure than I would like, but it is not bad to the point of making them uncomfortable.
So, these are definitely not a casual purchase in any sense, but if you are considering them you probably know that.
100% a professional tool, I'm not surprised that HEDD now makes an alternative model more tuned to audiophile tastes.