diff --git a/libs/ardour/ardour/plugin_insert.h b/libs/ardour/ardour/plugin_insert.h
index 291dda4231..3e233ba6c1 100644
--- a/libs/ardour/ardour/plugin_insert.h
+++ b/libs/ardour/ardour/plugin_insert.h
@@ -111,8 +111,8 @@ class LIBARDOUR_API PluginInsert : public Processor
 	// route is not a friend class, it owns us
 	bool set_count      (uint32_t num);
 	void set_outputs    (const ChanCount&);
-	void set_strict_io  (bool b) { _strict_io = b; }
-	void set_custom_cfg (bool b) { _custom_cfg = b; }
+	void set_strict_io  (bool b);
+	void set_custom_cfg (bool b);
 	// end C++ class slavery!
 
 	uint32_t get_count  () const { return _plugins.size(); }
@@ -209,6 +209,7 @@ class LIBARDOUR_API PluginInsert : public Processor
 	PBD::Signal2<void,BufferSet*, BufferSet*> AnalysisDataGathered;
 	PBD::Signal0<void> PluginIoReConfigure;
 	PBD::Signal0<void> PluginMapChanged;
+	PBD::Signal0<void> PluginConfigChanged;
 
 	/** Enumeration of the ways in which we can match our insert's
 	 *  IO to that of the plugin(s).
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index 9e55979a24..78f46275f7 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -86,6 +86,16 @@ PluginInsert::~PluginInsert ()
 {
 }
 
+void
+PluginInsert::set_strict_io (bool b)
+{
+	bool changed = _strict_io != b;
+	_strict_io = b;
+	if (changed) {
+		PluginConfigChanged (); /* EMIT SIGNAL */
+	}
+}
+
 bool
 PluginInsert::set_count (uint32_t num)
 {
@@ -111,12 +121,14 @@ PluginInsert::set_count (uint32_t num)
 				/* XXX do something */
 			}
 		}
+		PluginConfigChanged (); /* EMIT SIGNAL */
 
 	} else if (num < _plugins.size()) {
 		uint32_t diff = _plugins.size() - num;
 		for (uint32_t n= 0; n < diff; ++n) {
 			_plugins.pop_back();
 		}
+		PluginConfigChanged (); /* EMIT SIGNAL */
 	}
 
 	return true;
@@ -126,7 +138,21 @@ PluginInsert::set_count (uint32_t num)
 void
 PluginInsert::set_outputs (const ChanCount& c)
 {
+	bool changed = (_custom_out != c) && _custom_cfg;
 	_custom_out = c;
+	if (changed) {
+		PluginConfigChanged (); /* EMIT SIGNAL */
+	}
+}
+
+void
+PluginInsert::set_custom_cfg (bool b)
+{
+	bool changed = _custom_cfg != b;
+	_custom_cfg = b;
+	if (changed) {
+		PluginConfigChanged (); /* EMIT SIGNAL */
+	}
 }
 
 void
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 990ab14e28..6519980b68 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -2413,10 +2413,6 @@ Route::reset_plugin_insert (boost::shared_ptr<Processor> proc)
 bool
 Route::customize_plugin_insert (boost::shared_ptr<Processor> proc, uint32_t count, ChanCount outs)
 {
-	if (_strict_io) {
-		return false;
-	}
-
 	boost::shared_ptr<PluginInsert> pi;
 	if ((pi = boost::dynamic_pointer_cast<PluginInsert>(proc)) == 0) {
 		return false;
@@ -2441,7 +2437,6 @@ Route::customize_plugin_insert (boost::shared_ptr<Processor> proc, uint32_t coun
 		Glib::Threads::RWLock::WriterLock lm (_processor_lock);
 		ProcessorState pstate (this);
 
-		assert (!pi->strict_io ());
 		bool      old_cust = pi->custom_cfg ();
 		uint32_t  old_cnt  = pi->get_count ();
 		ChanCount old_chan = pi->output_streams ();