If you want to stream live music, e.g. singer and guitar over Zoom, there are some critical settings you need to change. Zoom is optimised for intelligibility of speech and can make quite a mess of anything that is not speech. Guitars can be particularly badly affected. However, there are specific settings you can use to turn off this processing.
In the Zoom App go to Settings, Audio, and click the Advanced button.

Enable the option to Enable Original Sound from microphone. For good measure you can also disable noise suppression.
When you are in the meeting you will then see an additional button at the top of the screen.

If it’s blue then you are using original (unprocessed) sound, which is best for music. The labelling is confusing, but tells you what will happen if you click the button. Blue means original, and if you click on the button it will turn off original sound and revert to normal processing.
If you’re streaming from your phone, there are similar settings in the app.
Remember that you need to enable these settings before joining the meeting.
Whilst this setting will help with audio quality, it will not enable musicians in several different places to play at the same time because of the inherent latency (delay) in internet streaming, and you will not be able to keep in time with each other.
If you’re looking to stream pre-recorded music over Zoom, check our page on sharing audio and video.