On stage, 15:05. The interface enumerated fine — USB bus, ALSA card 3 — and
the graph still had no trace of it, because PipeWire had it on the
input:analog-stereo profile: zero sinks, microphone ports only. Presence
was never the question.

pro-audio is the only profile on this device that carries a sink at all, so
there was no choice to make. Switched, and Master linked to it by hand;
check-audio-graph now passes its own monitor-path test and reports the
interface clocking at realtime across three samples.

Master still feeds the laptop too, deliberately, until the PA is confirmed
audible. Both the cut command and the durable Ardour-side fix are on the
card, because hand-made links do not survive a restart.