[RE: noise canceling headphones] [I am not an electrical engineer] I think that noise canceling headphones require at least one microphone, some op-amps, and

[RE: noise canceling headphones] [I am not an electrical engineer] I think that noise canceling headphones require at least one microphone, some op-amps, and some digital circuitry to sample analog signals, process those samples, and then perform digital to analog conversion to put the canceling signal back in the audio stream. Line level audio, can't power all that. Not enough current. Not enough voltage. So you need a battery or USB or a wall wart. Or you put some big ear pads on ordinary headphones...I have some for my ATH-MX50's I bought on eBay. They are about an inch think and filter out a lot of ambient sound. But perhaps I digress. Or maybe not. Thick earpads provide passive noise reduction without batteries and a set of ATH-MX50's plus earpads will set you back about $200, but you might get by with less expensive MX-30's or even MX-20's...indeed, some MX-20's plus some thick earpads from eBay is the simplest thing that might work.