Bought a 115V to USB Adaptor. I don't believe I've even got a year
usage out of it. Had a power outage and an external processor,
serving for SPDIF red-laser audio to analogue conversion, would not
power back up. (I like it for when mixing processed signals for it's
part as an oversamped reference signal.)

Better the USB adaptor than the audio processor unit, once I
remembered it was drawing USB power from a 115V source.

My first experience having bought a USB power adaptor. Also
apparently popular variously for charging units. So I guess they're
cheap, don't last, and hopefully wouldn't be dangerous enough to feed
a straight 115V through.

Not that drawing USB power for the SPDIF converter from a computer was
an issue in the first place. I just can't recall if I paid more than
$1US from a Chinese market.