ZynAddSubFX: initialize IO engine after setting up synth instance

plugins/zynaddsubfx/LocalZynAddSubFx.cpp

@@ -42,7 +42,7 @@ int LocalZynAddSubFx::s_instanceCount = 0;
 
 LocalZynAddSubFx::LocalZynAddSubFx() :
 	m_master( NULL ),
-	m_ioEngine( new NulEngine )
+	m_ioEngine( NULL )
 {
 	for( int i = 0; i < NumKeys; ++i )
 	{
@@ -74,6 +74,8 @@ LocalZynAddSubFx::LocalZynAddSubFx() :
 
 	++s_instanceCount;
 
+	m_ioEngine = new NulEngine;
+
 	m_master = new Master();
 	m_master->swaplr = 0;
 }