Testtone - make quite quiet

src/main_testtone.cc

@@ -25,7 +25,7 @@ void AudioCallback(
     for (size_t i = 0; i < size; i += 2) {
         osc.SetAmp(1.0);
         osc_out = osc.Process();
-        //Set the left and right outputs
+        osc_out *= 0.1;
         out[i] = osc_out;
         out[i + 1] = osc_out;
     }