diff --git a/output_i2s_f32.h b/output_i2s_f32.h
index abcc606..bfea439 100644
--- a/output_i2s_f32.h
+++ b/output_i2s_f32.h
@@ -1,6 +1,6 @@
 /*
  *  *****    output_i2s_f32.h  *****
- * 
+ *
  * Audio Library for Teensy 3.X
  * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
  *
@@ -26,7 +26,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
- /* 
+ /*
  *  Extended by Chip Audette, OpenAudio, May 2019
  *  Converted to F32 and to variable audio block length
  *	The F32 conversion is under the MIT License.  Use at your own risk.
@@ -47,14 +47,20 @@ class AudioOutputI2S_F32 : public AudioStream_F32
 //GUI: inputs:2, outputs:0  //this line used for automatic generation of GUI node
 public:
     //uses default AUDIO_SAMPLE_RATE and BLOCK_SIZE_SAMPLES from AudioStream.h:
-	AudioOutputI2S_F32(void) : AudioStream_F32(2, inputQueueArray)	{ begin();} 
+	AudioOutputI2S_F32(void) : AudioStream_F32(2, inputQueueArray)	{ begin();}
 	// Allow variable sample rate and block size:
 	AudioOutputI2S_F32(const AudioSettings_F32 &settings) : AudioStream_F32(2, inputQueueArray)
-	{ 
+	{
 		sample_rate_Hz = settings.sample_rate_Hz;
 		audio_block_samples = settings.audio_block_samples;
-		begin(); 	
+		begin();
 	}
+
+    // outputScale is a gain control for both left and right.  If set exactly
+    // to 1.0f it is left as a pass-through.
+    void setGain(float _oscale) {
+       outputScale = _oscale;
+       }
 	virtual void update(void);
 	void begin(void);
 	void begin(bool);
@@ -75,7 +81,7 @@ public:
 	static void scale_f32_to_i16( float32_t *p_f32, float32_t *p_i16, int len) ;
 	static void scale_f32_to_i24( float32_t *p_f32, float32_t *p_i16, int len) ;
 	static void scale_f32_to_i32( float32_t *p_f32, float32_t *p_i32, int len) ;
-	
+
 	static float setI2SFreq_T3(const float);  // I2S clock for T3,x
 protected:
 	AudioOutputI2S_F32(int dummy): AudioStream_F32(2, inputQueueArray) {} // to be used only inside AudioOutputI2Sslave !!
@@ -101,6 +107,7 @@ private:
 	static float sample_rate_Hz;
 	static int audio_block_samples;
 	volatile uint8_t enabled = 1;
+    float outputScale = 1.0f;  // Quick volume control
 };
 
 class AudioOutputI2Sslave_F32 : public AudioOutputI2S_F32