diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1f273bb4b..22ea7df91 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1143,14 +1143,15 @@ set (PCH_SOURCES
 	sound/mididevices/music_softsynth_mididevice.cpp
 	sound/mididevices/music_timidity_mididevice.cpp
 	sound/mididevices/music_wildmidi_mididevice.cpp
+	sound/midisources/midisource.cpp
+	sound/midisources/midisource_mus.cpp
+	sound/midisources/midisource_smf.cpp
+	sound/midisources/midisource_hmi.cpp
+	sound/midisources/midisource_xmi.cpp
 	sound/musicformats/music_cd.cpp
 	sound/musicformats/music_dumb.cpp
 	sound/musicformats/music_gme.cpp
 	sound/musicformats/music_libsndfile.cpp
-	sound/musicformats/music_mus_midiout.cpp
-	sound/musicformats/music_smf_midiout.cpp
-	sound/musicformats/music_hmi_midiout.cpp
-	sound/musicformats/music_xmi_midiout.cpp
 	sound/musicformats/music_midistream.cpp
 	sound/musicformats/music_opl.cpp
 	sound/musicformats/music_stream.cpp
@@ -1354,6 +1355,7 @@ source_group("Audio Files\\Timidity" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE
 source_group("Audio Files\\Timiditypp" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/sound/timiditypp/.+")
 source_group("Audio Files\\WildMidi" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/sound/wildmidi/.+")
 source_group("Audio Files\\MIDI Devices" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/sound/mididevices/.+")
+source_group("Audio Files\\MIDI Sources" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/sound/midisources/.+")
 source_group("Audio Files\\Music formats" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/sound/musicformats/.+")
 source_group("External\\Math" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/math/.+")
 source_group("External\\RapidJSON" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/rapidjson/.+")
diff --git a/src/sound/i_music.cpp b/src/sound/i_music.cpp
index fe307f614..47fdcc04a 100644
--- a/src/sound/i_music.cpp
+++ b/src/sound/i_music.cpp
@@ -117,13 +117,13 @@ CUSTOM_CVAR (Float, snd_musicvolume, 0.5f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 	else
 	{
 		// Set general music volume.
-		if (GSnd != NULL)
+		if (GSnd != nullptr)
 		{
 			GSnd->SetMusicVolume(clamp<float>(self * relative_volume, 0, 1));
 		}
 		// For music not implemented through the digital sound system,
 		// let them know about the change.
-		if (currSong != NULL)
+		if (currSong != nullptr)
 		{
 			currSong->MusicVolumeChanged();
 		}
@@ -178,7 +178,7 @@ void I_ShutdownMusic(bool onexit)
 	if (currSong)
 	{
 		S_StopMusic (true);
-		assert (currSong == NULL);
+		assert (currSong == nullptr);
 	}
 	Timidity::FreeAll();
 	if (onexit)
@@ -207,7 +207,7 @@ MusInfo::MusInfo()
 
 MusInfo::~MusInfo ()
 {
-	if (currSong == this) currSong = NULL;
+	if (currSong == this) currSong = nullptr;
 }
 
 //==========================================================================
@@ -233,7 +233,7 @@ void MusInfo::Start(bool loop, float rel_vol, int subsong)
 	if (m_Status == MusInfo::STATE_Playing)
 		currSong = this;
 	else
-		currSong = NULL;
+		currSong = nullptr;
 		
 	// Notify the sound system of the changed relative volume
 	snd_musicvolume.Callback();
@@ -299,12 +299,12 @@ FString MusInfo::GetStats()
 
 MusInfo *MusInfo::GetOPLDumper(const char *filename)
 {
-	return NULL;
+	return nullptr;
 }
 
 MusInfo *MusInfo::GetWaveDumper(const char *filename, int rate)
 {
-	return NULL;
+	return nullptr;
 }
 
 //==========================================================================
@@ -331,7 +331,7 @@ static MIDISource *CreateMIDISource(FileReader &reader, EMIDIType miditype)
 		return new XMISong(reader);
 
 	default:
-		return NULL;
+		return nullptr;
 	}
 }
 
@@ -404,7 +404,7 @@ static EMIDIType IdentifyMIDIType(uint32_t *id, int size)
 
 MusInfo *I_RegisterSong (FileReader *reader, MidiDeviceSetting *device)
 {
-	MusInfo *info = NULL;
+	MusInfo *info = nullptr;
 	const char *fmt;
 	uint32_t id[32/4];
 
@@ -431,11 +431,11 @@ MusInfo *I_RegisterSong (FileReader *reader, MidiDeviceSetting *device)
 		{
 			delete[] gzipped;
 			delete reader;
-			return NULL;
+			return nullptr;
 		}
 		delete reader;
 
-		MemoryArrayReader *memreader = new MemoryArrayReader(NULL, 0);
+		MemoryArrayReader *memreader = new MemoryArrayReader(nullptr, 0);
 		if (!ungzip(gzipped, len, memreader->GetArray()))
 		{
 			delete[] gzipped;
@@ -460,32 +460,41 @@ MusInfo *I_RegisterSong (FileReader *reader, MidiDeviceSetting *device)
 		if (source == nullptr) return 0;
 		if (!source->isValid())
 		{
+			delete reader;
 			delete source;
 			return 0;
 		}
 		
 		// fixme: device and streamer need to be handled individually.
-		EMidiDevice devtype = device == NULL? MDEV_DEFAULT : (EMidiDevice)device->device;
+		EMidiDevice devtype = device == nullptr? MDEV_DEFAULT : (EMidiDevice)device->device;
 #ifndef _WIN32
 		// non-Windows platforms don't support MDEV_MMAPI so map to MDEV_SNDSYS
 		if (devtype == MDEV_MMAPI)
 			devtype = MDEV_SNDSYS;
 #endif
 
+		MIDIStreamer *streamer = nullptr;
 retry_as_sndsys:
-		info = CreateMIDIStreamer(devtype, device != NULL? device->args.GetChars() : "");
+		streamer = CreateMIDIStreamer(devtype, device != nullptr? device->args.GetChars() : "");
 
-		if (info == NULL && devtype != MDEV_SNDSYS && snd_mididevice < 0)
+		if (streamer == nullptr && devtype != MDEV_SNDSYS && snd_mididevice < 0)
 		{
 			devtype = MDEV_SNDSYS;
 			goto retry_as_sndsys;
 		}
 #ifdef _WIN32
-		if (info == NULL && devtype != MDEV_MMAPI && snd_mididevice >= 0)
+		if (streamer == nullptr && devtype != MDEV_MMAPI && snd_mididevice >= 0)
 		{
-			info = CreateMIDIStreamer(MDEV_MMAPI, "");
+			 streamer = CreateMIDIStreamer(MDEV_MMAPI, "");
 		}
 #endif
+		if (streamer == nullptr)
+		{
+			delete reader;
+			return 0;
+		}
+		streamer->SetMIDISource(source);
+		info = streamer;
 	}
 
 	// Check for various raw OPL formats
@@ -494,10 +503,10 @@ retry_as_sndsys:
 		(id[0] == MAKE_ID('D','B','R','A') && id[1] == MAKE_ID('W','O','P','L')) ||		// DosBox Raw OPL
 		(id[0] == MAKE_ID('A','D','L','I') && *((uint8_t *)id + 4) == 'B'))		// Martin Fernandez's modified IMF
 	{
-		info = new OPLMUSSong (*reader, device != NULL? device->args.GetChars() : "");
+		info = new OPLMUSSong (*reader, device != nullptr? device->args.GetChars() : "");
 	}
 	// Check for game music
-	else if ((fmt = GME_CheckFormat(id[0])) != NULL && fmt[0] != '\0')
+	else if ((fmt = GME_CheckFormat(id[0])) != nullptr && fmt[0] != '\0')
 	{
 		info = GME_OpenSong(*reader, fmt);
 	}
@@ -512,7 +521,7 @@ retry_as_sndsys:
 		if (info != nullptr) reader = nullptr;
 	}
 
-    if (info == NULL)
+    if (info == nullptr)
     {
         // Check for CDDA "format"
         if (id[0] == (('R')|(('I')<<8)|(('F')<<16)|(('F')<<24)))
@@ -535,12 +544,12 @@ retry_as_sndsys:
         }
     }
 
-	if (reader != NULL) delete reader;
+	if (reader != nullptr) delete reader;
 
 	if (info && !info->IsValid ())
 	{
 		delete info;
-		info = NULL;
+		info = nullptr;
 	}
 
 	return info;
@@ -559,7 +568,7 @@ MusInfo *I_RegisterCDSong (int track, int id)
 	if (info && !info->IsValid ())
 	{
 		delete info;
-		info = NULL;
+		info = nullptr;
 	}
 
 	return info;
@@ -649,7 +658,7 @@ static bool ungzip(uint8_t *data, int complen, TArray<uint8_t> &newdata)
 
 void I_UpdateMusic()
 {
-	if (currSong != NULL)
+	if (currSong != nullptr)
 	{
 		currSong->Update();
 	}
@@ -686,7 +695,7 @@ CCMD(testmusicvol)
 {
 	if (argv.argc() > 1) 
 	{
-		relative_volume = (float)strtod(argv[1], NULL);
+		relative_volume = (float)strtod(argv[1], nullptr);
 		snd_musicvolume.Callback();
 	}
 	else
@@ -701,7 +710,7 @@ CCMD(testmusicvol)
 
 ADD_STAT(music)
 {
-	if (currSong != NULL)
+	if (currSong != nullptr)
 	{
 		return currSong->GetStats();
 	}
@@ -721,14 +730,14 @@ UNSAFE_CCMD (writeopl)
 {
 	if (argv.argc() == 2)
 	{
-		if (currSong == NULL)
+		if (currSong == nullptr)
 		{
 			Printf ("No song is currently playing.\n");
 		}
 		else
 		{
 			MusInfo *dumper = currSong->GetOPLDumper(argv[1]);
-			if (dumper == NULL)
+			if (dumper == nullptr)
 			{
 				Printf ("Current song cannot be saved as OPL data.\n");
 			}
@@ -759,14 +768,14 @@ UNSAFE_CCMD (writewave)
 {
 	if (argv.argc() >= 2 && argv.argc() <= 3)
 	{
-		if (currSong == NULL)
+		if (currSong == nullptr)
 		{
 			Printf ("No song is currently playing.\n");
 		}
 		else
 		{
 			MusInfo *dumper = currSong->GetWaveDumper(argv[1], argv.argc() == 3 ? atoi(argv[2]) : 0);
-			if (dumper == NULL)
+			if (dumper == nullptr)
 			{
 				Printf ("Current song cannot be saved as wave data.\n");
 			}
@@ -835,7 +844,7 @@ UNSAFE_CCMD (writemidi)
 
 	source->CreateSMF(midi, 1);
 	auto f = FileWriter::Open(argv[2]);
-	if (f == NULL)
+	if (f == nullptr)
 	{
 		Printf("Could not open %s.\n", argv[2]);
 		return;
diff --git a/src/sound/i_musicinterns.h b/src/sound/i_musicinterns.h
index f6c247b57..b0b4c297a 100644
--- a/src/sound/i_musicinterns.h
+++ b/src/sound/i_musicinterns.h
@@ -7,7 +7,7 @@
 #include "s_sound.h"
 #include "files.h"
 #include "wildmidi/wildmidi_lib.h"
-#include "midisources.h"
+#include "midisources/midisource.h"
 
 void I_InitMusicWin32 ();
 
diff --git a/src/sound/midisource.cpp b/src/sound/midisources/midisource.cpp
similarity index 99%
rename from src/sound/midisource.cpp
rename to src/sound/midisources/midisource.cpp
index 6c639709a..acb09fd56 100644
--- a/src/sound/midisource.cpp
+++ b/src/sound/midisources/midisource.cpp
@@ -35,7 +35,7 @@
 
 
 #include "i_musicinterns.h"
-#include "midisources.h"
+#include "midisource.h"
 
 
 char MIDI_EventLengths[7] = { 2, 2, 2, 2, 1, 1, 2 };
diff --git a/src/sound/midisources.h b/src/sound/midisources/midisource.h
similarity index 100%
rename from src/sound/midisources.h
rename to src/sound/midisources/midisource.h
diff --git a/src/sound/musicformats/music_hmi_midiout.cpp b/src/sound/midisources/midisource_hmi.cpp
similarity index 99%
rename from src/sound/musicformats/music_hmi_midiout.cpp
rename to src/sound/midisources/midisource_hmi.cpp
index d961c29c1..c2ce9b1fc 100644
--- a/src/sound/musicformats/music_hmi_midiout.cpp
+++ b/src/sound/midisources/midisource_hmi.cpp
@@ -39,7 +39,7 @@
 #include "doomdef.h"
 #include "m_swap.h"
 #include "files.h"
-#include "midisources.h"
+#include "midisource.h"
 
 // MACROS ------------------------------------------------------------------
 
diff --git a/src/sound/musicformats/music_mus_midiout.cpp b/src/sound/midisources/midisource_mus.cpp
similarity index 100%
rename from src/sound/musicformats/music_mus_midiout.cpp
rename to src/sound/midisources/midisource_mus.cpp
diff --git a/src/sound/musicformats/music_smf_midiout.cpp b/src/sound/midisources/midisource_smf.cpp
similarity index 100%
rename from src/sound/musicformats/music_smf_midiout.cpp
rename to src/sound/midisources/midisource_smf.cpp
diff --git a/src/sound/musicformats/music_xmi_midiout.cpp b/src/sound/midisources/midisource_xmi.cpp
similarity index 100%
rename from src/sound/musicformats/music_xmi_midiout.cpp
rename to src/sound/midisources/midisource_xmi.cpp
diff --git a/src/sound/music_midi_base.cpp b/src/sound/music_midi_base.cpp
index 810dd7e12..33c36842a 100644
--- a/src/sound/music_midi_base.cpp
+++ b/src/sound/music_midi_base.cpp
@@ -54,7 +54,6 @@ static bool		nummididevicesset;
 
 static void AddDefaultMidiDevices(FOptionValues *opt)
 {
-	int p;
 	FOptionValues::Pair *pair = &opt->mValues[opt->mValues.Reserve(NUM_DEF_DEVICES)];
 	pair[0].Text = "FluidSynth";
 	pair[0].Value = -5.0;