diff --git a/libs/ardour/ardour/audiosource.h b/libs/ardour/ardour/audiosource.h
index 73adc02944..632b34636a 100644
--- a/libs/ardour/ardour/audiosource.h
+++ b/libs/ardour/ardour/audiosource.h
@@ -103,25 +103,10 @@ class LIBARDOUR_API AudioSource : virtual public Source,
 	/** @return true if the each source sample s must be clamped to -1 < s < 1 */
 	virtual bool clamped_at_unity () const = 0;
 
-	static void allocate_working_buffers (samplecnt_t framerate);
-
   protected:
 	static bool _build_missing_peakfiles;
 	static bool _build_peakfiles;
 
-	/* these collections of working buffers for supporting
-	   playlist's reading from potentially nested/recursive
-	   sources assume SINGLE THREADED reads by the butler
-	   thread, or a lock around calls that use them.
-	*/
-
-	static std::vector<boost::shared_array<Sample> > _mixdown_buffers;
-	static std::vector<boost::shared_array<gain_t> > _gain_buffers;
-	static Glib::Threads::Mutex    _level_buffer_lock;
-
-	static void ensure_buffers_for_level (uint32_t, samplecnt_t);
-	static void ensure_buffers_for_level_locked (uint32_t, samplecnt_t);
-
 	samplecnt_t           _length;
 	std::string         _peakpath;
 
diff --git a/libs/ardour/audio_playlist_source.cc b/libs/ardour/audio_playlist_source.cc
index 5e96409602..0796f77e80 100644
--- a/libs/ardour/audio_playlist_source.cc
+++ b/libs/ardour/audio_playlist_source.cc
@@ -52,7 +52,6 @@ AudioPlaylistSource::AudioPlaylistSource (Session& s, const ID& orig, const std:
 	, _playlist_channel (chn)
 {
 	AudioSource::_length = len;
-	ensure_buffers_for_level (_level, _session.sample_rate());
 }
 
 AudioPlaylistSource::AudioPlaylistSource (Session& s, const XMLNode& node)
@@ -117,16 +116,12 @@ AudioPlaylistSource::set_state (const XMLNode& node, int version, bool with_desc
 		throw failed_constructor ();
 	}
 
-	ensure_buffers_for_level (_level, _session.sample_rate());
-
 	return 0;
 }
 
 samplecnt_t
 AudioPlaylistSource::read_unlocked (Sample* dst, samplepos_t start, samplecnt_t cnt) const
 {
-	boost::shared_array<Sample> sbuf;
-	boost::shared_array<gain_t> gbuf;
 	samplecnt_t to_read;
 	samplecnt_t to_zero;
 
@@ -143,16 +138,8 @@ AudioPlaylistSource::read_unlocked (Sample* dst, samplepos_t start, samplecnt_t
 		to_zero = 0;
 	}
 
-	{
-		/* Don't need to hold the lock for the actual read, and
-		   actually, we cannot, but we do want to interlock
-		   with any changes to the list of buffers caused
-		   by creating new nested playlists/sources
-		*/
-		Glib::Threads::Mutex::Lock lm (_level_buffer_lock);
-		sbuf = _mixdown_buffers[_level-1];
-		gbuf = _gain_buffers[_level-1];
-	}
+	boost::scoped_array<float> sbuf(new float[to_read]);
+	boost::scoped_array<gain_t> gbuf(new gain_t[to_read]);
 
 	boost::dynamic_pointer_cast<AudioPlaylist>(_playlist)->read (dst, sbuf.get(), gbuf.get(), start+_playlist_offset, to_read, _playlist_channel);
 
diff --git a/libs/ardour/audiosource.cc b/libs/ardour/audiosource.cc
index 33aaaa9bc5..d72975e46e 100644
--- a/libs/ardour/audiosource.cc
+++ b/libs/ardour/audiosource.cc
@@ -72,9 +72,6 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
-Glib::Threads::Mutex AudioSource::_level_buffer_lock;
-vector<boost::shared_array<Sample> > AudioSource::_mixdown_buffers;
-vector<boost::shared_array<gain_t> > AudioSource::_gain_buffers;
 bool AudioSource::_build_missing_peakfiles = false;
 
 /** true if we want peakfiles (e.g. if we are displaying a GUI) */
@@ -1138,49 +1135,3 @@ AudioSource::mark_streaming_write_completed (const Lock& lock)
 		PeaksReady (); /* EMIT SIGNAL */
 	}
 }
-
-void
-AudioSource::allocate_working_buffers (samplecnt_t framerate)
-{
-	Glib::Threads::Mutex::Lock lm (_level_buffer_lock);
-
-
-	/* Note: we don't need any buffers allocated until
-	   a level 1 audiosource is created, at which
-	   time we'll call ::ensure_buffers_for_level()
-	   with the right value and do the right thing.
-	*/
-
-	if (!_mixdown_buffers.empty()) {
-		ensure_buffers_for_level_locked ( _mixdown_buffers.size(), framerate);
-	}
-}
-
-void
-AudioSource::ensure_buffers_for_level (uint32_t level, samplecnt_t sample_rate)
-{
-	Glib::Threads::Mutex::Lock lm (_level_buffer_lock);
-	ensure_buffers_for_level_locked (level, sample_rate);
-}
-
-void
-AudioSource::ensure_buffers_for_level_locked (uint32_t level, samplecnt_t sample_rate)
-{
-	samplecnt_t nframes = PlaybackBuffer<Sample>::power_of_two_size ((samplecnt_t) floor (Config->get_audio_playback_buffer_seconds() * sample_rate));
-
-	/* this may be called because either "level" or "sample_rate" have
-	 * changed. and it may be called with "level" smaller than the current
-	 * number of buffers, because a new compound region has been created at
-	 * a more shallow level than the deepest one we currently have.
-	 */
-
-	uint32_t limit = max ((size_t) level, _mixdown_buffers.size());
-
-	_mixdown_buffers.clear ();
-	_gain_buffers.clear ();
-
-	for (uint32_t n = 0; n < limit; ++n) {
-		_mixdown_buffers.push_back (boost::shared_array<Sample> (new Sample[nframes]));
-		_gain_buffers.push_back (boost::shared_array<gain_t> (new gain_t[nframes]));
-	}
-}
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index bccae20c8f..9929cde023 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -4191,8 +4191,6 @@ Session::config_changed (std::string p, bool ours)
 		_solo_cut_control->Changed (true, Controllable::NoGroup);
 	} else if (p == "timecode-offset" || p == "timecode-offset-negative") {
 		last_timecode_valid = false;
-	} else if (p == "playback-buffer-seconds") {
-		AudioSource::allocate_working_buffers (sample_rate());
 	} else if (p == "ltc-sink-port") {
 		reconnect_ltc_output ();
 	} else if (p == "timecode-generator-offset") {