Originally Posted By: jazzmammal
The headphone out of modern laptop is more than good enough for live gigging. One thing though, running it while plugged in with an AC power cable will cause weird noises through your PA and that will be your first question here after the gig. You need to either use a two prong adapter to lift the ground or run it off the battery.
That depends on your power supply adaptor. There are some that need a galvanic isolation, others don't because of their internal workings.

If you get "weird noises" when your laptop is plugged in, get one of the rather cheap adaptors from somebody like Radio Shack or your preferred dealer of electronic equipment. They know this effect and the means to solve it.

If you've never heard about it look for galvanic isolation on Wikipedia and continue from there.

Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build