Regarding a shorter cable:

The connector on the HD560S is a locking 2.5mm connector, so not any cable is going to work. The easiest way to get one is probably by buying the HD5X8/HD5X9 cable from Sennheiser (1.2m long and 3.5mm terminated). While it is designed for other 500 series headphones, it works perfectly well for the 560S too (no idea why Sennheiser doesn’t mention that anywhere). Alternatively look for a third party cable.