The eternal question to the company (Beyerdynamic) is why this model is not updated with removable cable, but most of all, why the 16Ω version has remained out of the offer and out of production, being produced at the time only as a limited production run. In these mobile times that headphone is reportedly easier to run of the smartphone and laptop without the need for USB DAC/amp.
For anyone who would now want to enter "the debate" with the "argument" that the 32Ω version is efficient enough, no, I would not agree with that, since I have spent some time with it, and run detailed comparisons with some other headphones that are often listed as a competitors within the price bracket/segment. This has more to do with the combination of the impedance (less important) and relatively low sensitivity (96db), the latter seems to be somewhat limiting factor.
For the sound quality, this headphone would have been much better without either bass-reflex system (which seems to yield an exaggerated bass response, ruining what could have otherwise been a fantastic headphone for the price) or with some serious dampening adjustments to the driver and/or the membrane, in order to make the bass response less exaggerated .
This headphone has otherwise excellent sonic potential, great natural tonality, speed, detail retrieval.
To me - the (at times) overwhelming bass response simply kills the joy.