diff --git a/libs/ardour/ardour/plug_insert_base.h b/libs/ardour/ardour/plug_insert_base.h
index a4e9d542ef..7c9cff6986 100644
--- a/libs/ardour/ardour/plug_insert_base.h
+++ b/libs/ardour/ardour/plug_insert_base.h
@@ -103,6 +103,33 @@ public:
 		Variant         _value;
 	};
 
+	/** Enumeration of the ways in which we can match our insert's
+	 *  IO to that of the plugin(s).
+	 */
+	enum MatchingMethod {
+		Impossible,  ///< we can't
+		Delegate,    ///< we are delegating to the plugin, and it can handle it
+		NoInputs,    ///< plugin has no inputs, so anything goes
+		ExactMatch,  ///< our insert's inputs are the same as the plugin's
+		Replicate,   ///< we have multiple instances of the plugin
+		Split,       ///< we copy one of our insert's inputs to multiple plugin inputs
+		Hide,        ///< we `hide' some of the plugin's inputs by feeding them silence
+	};
+
+	/** Description of how we can match our plugin's IO to our own insert IO */
+	struct Match {
+		Match () : method (Impossible), plugins (0), strict_io (false), custom_cfg (false) {}
+		Match (MatchingMethod m, int32_t p,
+				bool strict = false, bool custom = false, ChanCount h = ChanCount ())
+			: method (m), plugins (p), hide (h), strict_io (strict), custom_cfg (custom) {}
+
+		MatchingMethod method; ///< method to employ
+		int32_t plugins;       ///< number of copies of the plugin that we need
+		ChanCount hide;        ///< number of channels to hide
+		bool strict_io;        ///< force in == out
+		bool custom_cfg;       ///< custom config (if not strict)
+	};
+
 protected:
 	static std::shared_ptr<Plugin> plugin_factory (std::shared_ptr<Plugin>);
 
@@ -115,4 +142,6 @@ protected:
 
 } // namespace ARDOUR
 
+std::ostream& operator<<(std::ostream& o, const ARDOUR::PlugInsertBase::Match& m);
+
 #endif
diff --git a/libs/ardour/ardour/plugin_insert.h b/libs/ardour/ardour/plugin_insert.h
index bde43d256c..9de7629a5a 100644
--- a/libs/ardour/ardour/plugin_insert.h
+++ b/libs/ardour/ardour/plugin_insert.h
@@ -270,34 +270,6 @@ public:
 	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).
-	 */
-	enum MatchingMethod {
-		Impossible,  ///< we can't
-		Delegate,    ///< we are delegating to the plugin, and it can handle it
-		NoInputs,    ///< plugin has no inputs, so anything goes
-		ExactMatch,  ///< our insert's inputs are the same as the plugin's
-		Replicate,   ///< we have multiple instances of the plugin
-		Split,       ///< we copy one of our insert's inputs to multiple plugin inputs
-		Hide,        ///< we `hide' some of the plugin's inputs by feeding them silence
-	};
-
-	/** Description of how we can match our plugin's IO to our own insert IO */
-	struct Match {
-		Match () : method (Impossible), plugins (0), strict_io (false), custom_cfg (false) {}
-		Match (MatchingMethod m, int32_t p,
-				bool strict = false, bool custom = false, ChanCount h = ChanCount ())
-			: method (m), plugins (p), hide (h), strict_io (strict), custom_cfg (custom) {}
-
-		MatchingMethod method; ///< method to employ
-		int32_t plugins;       ///< number of copies of the plugin that we need
-		ChanCount hide;        ///< number of channels to hide
-		bool strict_io;        ///< force in == out
-		bool custom_cfg;       ///< custom config (if not strict)
-	};
-
 protected:
 	XMLNode& state () const;
 
@@ -427,6 +399,4 @@ private:
 
 } // namespace ARDOUR
 
-std::ostream& operator<<(std::ostream& o, const ARDOUR::PluginInsert::Match& m);
-
 #endif /* __ardour_plugin_insert_h__ */
diff --git a/libs/ardour/plug_insert_base.cc b/libs/ardour/plug_insert_base.cc
index 73eecdecce..e762cca9ab 100644
--- a/libs/ardour/plug_insert_base.cc
+++ b/libs/ardour/plug_insert_base.cc
@@ -400,3 +400,24 @@ PlugInsertBase::PluginPropertyControl::get_value () const
 {
 	return _value.to_double ();
 }
+
+std::ostream& operator<<(std::ostream& o, const ARDOUR::PlugInsertBase::Match& m)
+{
+	switch (m.method) {
+		case PlugInsertBase::Impossible: o << "Impossible"; break;
+		case PlugInsertBase::Delegate:   o << "Delegate"; break;
+		case PlugInsertBase::NoInputs:   o << "NoInputs"; break;
+		case PlugInsertBase::ExactMatch: o << "ExactMatch"; break;
+		case PlugInsertBase::Replicate:  o << "Replicate"; break;
+		case PlugInsertBase::Split:      o << "Split"; break;
+		case PlugInsertBase::Hide:       o << "Hide"; break;
+	}
+	o << " cnt: " << m.plugins
+		<< (m.strict_io ? " strict-io" : "")
+		<< (m.custom_cfg ? " custom-cfg" : "");
+	if (m.method == PlugInsertBase::Hide) {
+		o << " hide: " << m.hide;
+	}
+	o << "\n";
+	return o;
+}
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index 114ee3fc86..aaa5819b69 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -2259,7 +2259,7 @@ PluginInsert::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 	return private_can_support_io_configuration (in, out).method != Impossible;
 }
 
-PluginInsert::Match
+PlugInsertBase::Match
 PluginInsert::private_can_support_io_configuration (ChanCount const& in, ChanCount& out) const
 {
 	if (!_custom_cfg && _preset_out.n_audio () > 0) {
@@ -3236,24 +3236,3 @@ PluginInsert::clear_stats ()
 {
 	_stat_reset.store (1);
 }
-
-std::ostream& operator<<(std::ostream& o, const ARDOUR::PluginInsert::Match& m)
-{
-	switch (m.method) {
-		case PluginInsert::Impossible: o << "Impossible"; break;
-		case PluginInsert::Delegate:   o << "Delegate"; break;
-		case PluginInsert::NoInputs:   o << "NoInputs"; break;
-		case PluginInsert::ExactMatch: o << "ExactMatch"; break;
-		case PluginInsert::Replicate:  o << "Replicate"; break;
-		case PluginInsert::Split:      o << "Split"; break;
-		case PluginInsert::Hide:       o << "Hide"; break;
-	}
-	o << " cnt: " << m.plugins
-		<< (m.strict_io ? " strict-io" : "")
-		<< (m.custom_cfg ? " custom-cfg" : "");
-	if (m.method == PluginInsert::Hide) {
-		o << " hide: " << m.hide;
-	}
-	o << "\n";
-	return o;
-}