In the configuration section of your control panel you will notice that you can edit the maximum per user voice quality of your server. We put no limit to the voice quality you can have unlike some competitors.
The configuration default is 72000 (72Kbps) and we have found in our tests this is the best balance and happens to be the same voice quality as TeamSpeak 3's maximum. The maximum value you can enter is 130000 (130Kbps) while this does increase voice quality it can cause issues and lag for some of your users that have slower connections or less powerful computers. This is especially noticable if you have any high stress programs running like video games or compilers. Please note our servers are fully capable of serving the maximum for all of your users but issues that do pop up would be due to the limitations of your individual users.
The voice quality setting is all about balance. You don't want to set it too low or you will get lots of lag, and distored voice but you don't want it set too high or some of your individual users will have lag. It is advised that you find a sweet spot that works for all of your users, but 72000 is generally the defacto standard and you won't have any issues or lag at that setting. Setting the voice quality to anything above 130000 won't increase it any further and that is because that is the maximum that mumble can handle. You can read more about this setting from the official Mumble site https://wiki.mumble.info/wiki/Murmur.ini#bandwidth