Opensource Audio Project + Desktop Audio Capture = Lovely Preshow Music
Here's a neat, open source site that looks at Wikipedia activity and generates simple music based on what type of action was performed. The website is http://listen.hatnote.com/, but there's also an iOS app, and a github. It allows you to listen to Wikipedia and set various parameters as to what you're listening to, which I find lets you make nice, neutral-sounding audio every time.
It makes very relaxing music that I sometimes record and use for preshow music for smaller, artsy projects where this type of vibe fits. (I pre-record it so that I can fade it in and out using Isadora so that I don't have to hop between software while starting the show.)
Ahead of the performance, I'll open up the site and capture "x" minutes of preshow music using free software called OBS and iShowU Audio Capture to capture and record my own desktop audio, which leaves me with audio files I can then fade in and out easily using Isadora.
Hope some of you find all of this, or parts of it, interesting or helpful.
P.S. These instructions are only for Mac, but if someone based on Windows wants to contribute how to do this sort of audio routing and recording on Windows, that would be fabulous. The hatnote website and OBS will both work for Windows, it's just a matter of the free audio routing software and how to set it up really.