I have a usb interface that I run a condenser mic through to record vocals. Typically in ableton im used to just plugging on the interface and I can select on an option saying audio input device.

Can someone tell me how to do this on a Linux system that runs on RPI3?

im running this code:

1. ecasound -c -f:16,2,44100 \
        -a:1 -i monitor-track.wav -o alsa \ 

       -a:2 -i alsa -o new-track.wav