[on the client] add a local /etc/[pulse/]default.pa containing:

load-module module-tunnel-sink sink_name=rpi_tunnel server=tcp:192.168.2.13:4713 sink=bcm1

If you don't put a sink_name in, pulseaudio won't start. The sink refers to the sink name on the [server] side [determined via: pactl list | grep -C5 Sink | grep 'Name:']