Try setting the sample rate higher. Out of the box Wren used to run at a sample rate of 44.1 kHz, setting it to 88.2 kHz or 96 kHz makes it sound a lot better.

As of version 2015.9.10.0 I've made the default sample rate to be 88.2 kHz, but when you have an earlier install the existing INI file may still set the sample rate to a lower value. So, please check the Settings Screen F3.

In versions 2019.11.12.0 there was a bug where some audio rate (red) wires might turn blue (control rate). When this is the case redrawing these wires will help. This should not happen anymore in any later versions.

When this does not help please let me know about the issue. along with the badly performing patch.