diff --git a/libs/ardour/ardour/audioregion.h b/libs/ardour/ardour/audioregion.h
index f28296d81e..0b8215bfa4 100644
--- a/libs/ardour/ardour/audioregion.h
+++ b/libs/ardour/ardour/audioregion.h
@@ -121,9 +121,10 @@ class LIBARDOUR_API AudioRegion : public Region, public AudioReadable
 	                             samplecnt_t cnt,
 	                             uint32_t   chan_n = 0) const;
 
-	samplecnt_t master_read_at (Sample *buf, Sample *mixdown_buf, float *gain_buf,
-	                                    samplepos_t position, samplecnt_t cnt,
-	                                    uint32_t chan_n=0) const;
+	samplecnt_t master_read_at (Sample*     buf,
+	                            samplepos_t position,
+	                            samplecnt_t cnt,
+	                            uint32_t    chan_n=0) const;
 
 	samplecnt_t read_raw_internal (Sample*, samplepos_t, samplecnt_t, int channel) const;
 
diff --git a/libs/ardour/audioregion.cc b/libs/ardour/audioregion.cc
index 9af69c29b4..7d39ea18e7 100644
--- a/libs/ardour/audioregion.cc
+++ b/libs/ardour/audioregion.cc
@@ -475,8 +475,7 @@ AudioRegion::read (Sample* buf, samplepos_t pos, samplecnt_t cnt, int channel) c
 }
 
 samplecnt_t
-AudioRegion::master_read_at (Sample* buf, Sample* /*mixdown_buffer*/, float* /*gain_buffer*/,
-                             samplepos_t position, samplecnt_t cnt, uint32_t chan_n) const
+AudioRegion::master_read_at (Sample* buf, samplepos_t position, samplecnt_t cnt, uint32_t chan_n) const
 {
 	/* do not read gain/scaling/fades and do not count this disk i/o in statistics */
 
diff --git a/libs/ardour/lua_api.cc b/libs/ardour/lua_api.cc
index f69c9fbb82..6dc818ad90 100644
--- a/libs/ardour/lua_api.cc
+++ b/libs/ardour/lua_api.cc
@@ -1216,7 +1216,7 @@ LuaAPI::Rubberband::set_mapping (luabridge::LuaRef tbl)
 samplecnt_t
 LuaAPI::Rubberband::read (Sample* buf, samplepos_t pos, samplecnt_t cnt, int channel) const
 {
-	return _region->master_read_at (buf, NULL, NULL, _read_offset + pos, cnt, channel);
+	return _region->master_read_at (buf, _read_offset + pos, cnt, channel);
 }
 
 static void null_deleter (LuaAPI::Rubberband*) {}
diff --git a/libs/ardour/rb_effect.cc b/libs/ardour/rb_effect.cc
index 0665cfc221..e82ed01ddf 100644
--- a/libs/ardour/rb_effect.cc
+++ b/libs/ardour/rb_effect.cc
@@ -77,7 +77,6 @@ RBEffect::run (std::shared_ptr<Region> r, Progress* progress)
 	SourceList        nsrcs;
 	int               ret         = -1;
 	const samplecnt_t bufsize     = 8192;
-	gain_t*           gain_buffer = 0;
 	Sample**          buffers     = 0;
 	char              suffix[32];
 	string            new_name;
@@ -201,8 +200,7 @@ RBEffect::run (std::shared_ptr<Region> r, Progress* progress)
 		goto out;
 	}
 
-	gain_buffer = new gain_t[bufsize];
-	buffers     = new float*[channels];
+	buffers = new float*[channels];
 
 	for (uint32_t i = 0; i < channels; ++i) {
 		buffers[i] = new float[bufsize];
@@ -225,8 +223,6 @@ RBEffect::run (std::shared_ptr<Region> r, Progress* progress)
 				                region->start_sample () + region->position_sample ();
 
 				this_read = region->master_read_at (buffers[i],
-				                                    buffers[i],
-				                                    gain_buffer,
 				                                    this_position,
 				                                    this_time,
 				                                    i);
@@ -262,8 +258,6 @@ RBEffect::run (std::shared_ptr<Region> r, Progress* progress)
 				                region->start_sample () + region->position_sample ();
 
 				this_read = region->master_read_at (buffers[i],
-				                                    buffers[i],
-				                                    gain_buffer,
 				                                    this_position,
 				                                    this_time,
 				                                    i);
@@ -377,8 +371,6 @@ RBEffect::run (std::shared_ptr<Region> r, Progress* progress)
 
 out:
 
-	delete[] gain_buffer;
-
 	if (buffers) {
 		for (uint32_t i = 0; i < channels; ++i) {
 			delete[] buffers[i];
diff --git a/libs/ardour/st_stretch.cc b/libs/ardour/st_stretch.cc
index 424a3663a0..ab37198e0a 100644
--- a/libs/ardour/st_stretch.cc
+++ b/libs/ardour/st_stretch.cc
@@ -60,7 +60,6 @@ STStretch::run (std::shared_ptr<Region> r, Progress* progress)
 	SourceList        nsrcs;
 	int               ret         = -1;
 	const samplecnt_t bufsize     = 8192;
-	gain_t*           gain_buffer = 0;
 	Sample**          buffers     = 0;
 	char              suffix[32];
 	string            new_name;
@@ -181,8 +180,7 @@ STStretch::run (std::shared_ptr<Region> r, Progress* progress)
 		goto out;
 	}
 
-	gain_buffer = new gain_t[bufsize];
-	buffers     = new float*[channels];
+	buffers = new float*[channels];
 
 	for (uint32_t i = 0; i < channels; ++i) {
 		buffers[i] = new float[bufsize];
@@ -208,8 +206,6 @@ STStretch::run (std::shared_ptr<Region> r, Progress* progress)
 				                region->start () + region->position ();
 
 				this_read = region->master_read_at (buffers[i],
-				                                    buffers[i],
-				                                    gain_buffer,
 				                                    this_position,
 				                                    this_time,
 				                                    i);
@@ -319,8 +315,6 @@ STStretch::run (std::shared_ptr<Region> r, Progress* progress)
 
 out:
 
-	delete[] gain_buffer;
-
 	if (buffers) {
 		for (uint32_t i = 0; i < channels; ++i) {
 			delete[] buffers[i];