Personally I would rather keep cheap Chinese knockoff headphones full of nanotubes away from my brain. How do you know the pounding of a bass beat is not actually injecting nanotubes through the fabric and eventually migrating them with vibration into your brain? Even if there is "no chance of danger" (as if anyone has actually packaged nanotubes in an energetic, electromagnetically pumped environment near the human body) I would just not feel like it is something safe to have around. Imagine someone came up with an anti-smog filter for your nostrils that works based on "nano-packaged asbestos fibers" which have "no chance of being ingested"? If nano isn't critical and in a highly safety engineered package far from me (or at least something biologically created that I have a chance of breaking down), I don't want it.