I've used qjackctl, but I thought there might be a way to do it at a
lower level. Because, in qjackctl Connections, if I have no connections
set, I still hear the mono line-in coming directly out the left output.
If I then connect alsa_pcm:capture_1 to alsa_pcm:playback_1 and
playback_2, this seems to add extra connections, and sounds like it's a
bit like a chorus effect.
Or maybe there is a way to turn off the "automatic throughput", so only
the connections I see in qjackctl are actually made?