diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 7ce951fd31..403220f029 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -414,6 +414,8 @@ public:
 
 	void maybe_write_autosave ();
 
+	PBD::Signal0<void> SurroundObjectCountChanged;
+
 	/* Emitted when all i/o connections are complete */
 
 	PBD::Signal0<void> IOConnectionsComplete;
diff --git a/libs/ardour/surround_return.cc b/libs/ardour/surround_return.cc
index f66f841166..c2fba28dda 100644
--- a/libs/ardour/surround_return.cc
+++ b/libs/ardour/surround_return.cc
@@ -538,6 +538,7 @@ SurroundReturn::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_
 		URIMap::URIDs const& urids = URIMap::instance ().urids;
 		forge_int_msg (urids.surr_Settings, urids.surr_ChannelCount, _current_n_channels);
 #endif
+		_session.SurroundObjectCountChanged();  //EMIT SIGNAL
 	}
 
 	if (_have_au_renderer && _binaural_render_control->get_value () != 0 && _output_format_control->get_value () != 0) {