diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index 3fc6054b3e..4b4130aac9 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -1155,8 +1155,20 @@ int
 AudioEngine::client_real_time_priority ()
 {
 	if (!_backend) {
+		assert (0);
 		return PBD_RT_PRI_PROC;
 	}
+	if (!_backend->is_realtime ()) {
+		/* this is only an issue with the Dummy backend.
+		 * - with JACK, we require rt permissions.
+		 * - with ALSA/Pulseaudio this can only happen if rt permissions
+		 *   are n/a. Other atempts to get rt will fail likewise.
+		 *
+		 * perhaps:
+		 * TODO: use is_realtime () ? PBD_SCHED_FIFO : PBD_SCHED_OTHER
+		 */
+		return PBD_RT_PRI_PROC; // XXX
+	}
 
 	return _backend->client_real_time_priority();
 }
diff --git a/libs/ardour/automation_watch.cc b/libs/ardour/automation_watch.cc
index ea602a29c5..763e63a3aa 100644
--- a/libs/ardour/automation_watch.cc
+++ b/libs/ardour/automation_watch.cc
@@ -189,7 +189,7 @@ AutomationWatch::timer ()
 void
 AutomationWatch::thread ()
 {
-	pbd_set_thread_priority (pthread_self(), PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority() - 3);
+	pbd_set_thread_priority (pthread_self(), PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority() - 2);
 	pthread_set_name ("AutomationWatch");
 	while (_run_thread) {
 		Glib::usleep ((gulong) floor (Config->get_automation_interval_msecs() * 1000));
diff --git a/libs/ardour/convolver.cc b/libs/ardour/convolver.cc
index 2f94950836..112db53e2b 100644
--- a/libs/ardour/convolver.cc
+++ b/libs/ardour/convolver.cc
@@ -158,7 +158,7 @@ Convolution::restart ()
 	}
 
 	if (rv == 0) {
-		rv = _convproc.start_process (pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance ()->client_real_time_priority () - 2), PBD_SCHED_FIFO);
+		rv = _convproc.start_process (pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance ()->client_real_time_priority () - 1), PBD_SCHED_FIFO);
 	}
 
 	assert (rv == 0); // bail out in debug builds
diff --git a/libs/ardour/globals.cc b/libs/ardour/globals.cc
index efef182a74..90c2597df6 100644
--- a/libs/ardour/globals.cc
+++ b/libs/ardour/globals.cc
@@ -698,7 +698,7 @@ ARDOUR::init_post_engine (uint32_t start_cnt)
 		}
 	}
 
-	BaseUI::set_thread_priority (pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority () - 3));
+	BaseUI::set_thread_priority (pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority () - 2));
 
 	TransportMasterManager::instance ().restart ();
 }
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index b103a52621..5d71defc30 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -545,7 +545,7 @@ LV2Plugin::init(const void* c_plugin, samplecnt_t rate)
 	static const int32_t _min_block_length = 1;   // may happen during split-cycles
 	static const int32_t _max_block_length = 8192; // max possible (with all engines and during export)
 	static const int32_t rt_policy = PBD_SCHED_FIFO;
-	static const int32_t rt_priority = pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority () - 2);
+	static const int32_t rt_priority = pbd_absolute_rt_priority (PBD_SCHED_FIFO, AudioEngine::instance()->client_real_time_priority () - 1);
 	/* Consider updating max-block-size whenever the buffersize changes.
 	 * It requires re-instantiating the plugin (which is a non-realtime operation),
 	 * so it should be done lightly and only for plugins that require it.
diff --git a/libs/pbd/pthread_utils.cc b/libs/pbd/pthread_utils.cc
index 69f1072148..7226552160 100644
--- a/libs/pbd/pthread_utils.cc
+++ b/libs/pbd/pthread_utils.cc
@@ -321,6 +321,7 @@ pbd_absolute_rt_priority (int policy, int priority)
 	const int p_max = sched_get_priority_max (policy); // Linux: 99
 
 	if (priority == 0) {
+		assert (0);
 		priority = (p_min + p_max) / 2;
 	} else if (priority > 0) {
 		/* value relative to minium */