I asked my engineer uncle what he thinks about balanced headphone cables, and he looked at me a bit weird. He didn't know such things existed, and couldn't see why they would be any better than regular headphone cables.
Balanced preamp is completely different story though.
What kind of material is the capsule? Acetone is pretty good for removing glue residues.. But if the surface is painted it might remove the paint also^ so be careful
Just enjoying some Submotion Orchestra (sort of jazz influenced dubstep) on my DT48. This band is very well recorded and it shows. The DT48 sound fantastic.