Where would I find a USB charging cable for these headphones?

I’m a big fan of my Sony DR-BT22 Bluetooth headphones. But Sony stupidly built the charger to run off 110v, so it’s not that portable. You have to find a plug to charge it up.

I thought there might be a place online to create a USB charger. The wall wart reads:

INPUT: AC120V/ca120V, 60Hz 5W

There’s also the diagram with a diamond with a (-) inside, a C (open side facing right, and a diamond with a (+) inside. The plug tip is very small.

Is this a possibility or more trouble than it’s worth?

While USB does supply 5 volts, it maxes out at 500 milliamps, so you’d have to power it off two USB ports in parallel. Therefore, it’s a possibility, but probably more trouble than it’s worth.

Any device that charges via USB can be charged from any USB source. I replaced (almost) all of my USB chargers with a powered USB hub. I got one with a 110/220 V wall wart so I can use it in the US or Europe (with an adapter) and use it all the time when traveling. It doesn’t even have to be connected to a computer; just plug it into the wall then connect the device to the hub with a USB cable.

(The one exception I have found is my iPod which, for some reason, will not recharge when plugged into the hub unless it in turn is plugged into a powered-on computer. I don’t know why.)