Fixing mono/stereo switch.

UI.hpp

@@ -1983,7 +1983,7 @@ void set_treble(uint8_t value)
   configuration.treble = value;
 }
 
-void set_stereo(int8_t value)
+void set_stereo(uint8_t value)
 {
   if (value > ENC_STEREO_MAX)
     value = ENC_STEREO_MAX;
@@ -2413,13 +2413,15 @@ void set_mono(uint8_t mode)
 #endif
   if (mode == 0)
   {
-    set_stereo(configuration.stereo);
+    ep->setStereo(mapfloat(float(configuration.stereo), ENC_STEREO_MIN, ENC_STEREO_MAX, 0.0, 1.0));
     inverter.gain(-1.0); // change phase for second modulated delay (faked stereo mode)
+    configuration.mono = 0;
   }
   else
   {
-    set_stereo(ENC_STEREO_MIN);
+    ep->setStereo(0.0);
     inverter.gain(1.0);
+    configuration.mono = 1;
   }
 }