Sonic Pi 3.3.1 is configured to work with pulseaudio on the latest Raspberry Pi OS 2021-01-11. Although this is convenient it means that high end additional USB sound cards will not work with low latency with this configuration. This video demonstrates a script which will enable such cards to work with QjackCtl configured for lower latency.
The code can be downloaded from this repository
https://github.com/rbnpi/sonicpi-rpi-...