diff --git a/libs/backends/coreaudio/coreaudio_backend.cc b/libs/backends/coreaudio/coreaudio_backend.cc
index 0f1b637026..15e8c9f8b9 100644
--- a/libs/backends/coreaudio/coreaudio_backend.cc
+++ b/libs/backends/coreaudio/coreaudio_backend.cc
@@ -703,9 +703,8 @@ CoreAudioBackend::_start (bool for_latency_measurement)
 
 	engine.reconnect_ports ();
 
-	// force  an initial registration_callback() & latency re-compute
+	// force an initial registration_callback() & latency re-compute
 	_port_change_flag.store (1);
-	pre_process ();
 
 	_dsp_load_calc.reset ();
 	// all systems go.
diff --git a/libs/backends/portaudio/portaudio_backend.cc b/libs/backends/portaudio/portaudio_backend.cc
index c0bb2131fd..ab1044639a 100644
--- a/libs/backends/portaudio/portaudio_backend.cc
+++ b/libs/backends/portaudio/portaudio_backend.cc
@@ -702,6 +702,7 @@ PortAudioBackend::_start (bool for_latency_measurement)
 			stop ();
 			return ProcessThreadStartError;
 		}
+		_port_change_flag.store (1);
 	}
 
 	return NoError;