Sony has a sequel to 2015's MDR-1A headphones: MDR-1AM2.
These headphones have a "a newly developed 40mm HD driver unit" ("HD" because it is compatible with 100kHz frequencies), as well as aluminium-coated diaphragms and oxygen-free copper cables.
They're also, apparently, lighter than the previous model - which is only a good thing, especially if you're going to use them over long journeys.
If you prefer balanced connections over the standard 3.5mm then these headphones have you covered, as they offer the smaller jack too.
Sony is also offering a cable upgrade: the "Kimber Kable" can, according to the company, "seriously want to boost the quality of the sounds you are listening to". However, it will set you back another £180.
Should these headphones have piqued your interest, you'll find them available from early April and priced at £240.