Reported again after the monitor was wired up: 300% still sounded like 10%. The
monitor fix was right but could not show, because the sliders only changed the
settings panel's own state — the value reached the audio engine when the
operator clicked Save.
A level is set by ear, by dragging. It now applies on every move, to the monitor
and to the recorder mix alike; saving still persists it. Both halves were needed
and neither works alone.