to cut the above cable to just a few centimeters in length and then solder a female 3.5mm jack to make the DT-250 headphone able to make use of generic male to male 3.5mm cables?
Sure. Or you could just install a female 3.5mm jack in the headphone and replace that proprietary connector.
thanks for the reply and it would be nicer but it would require more work whilst also voiding the warranty (it's only a week old!) and if anything goes wrong, the headphone itself would still remain in good condition.