diff --git a/MicroDexed.ino b/MicroDexed.ino
index d3c5ef3..178545e 100644
--- a/MicroDexed.ino
+++ b/MicroDexed.ino
@@ -176,7 +176,7 @@ void setup()
   pinMode(SDCARD_CS_PIN, OUTPUT);
   pinMode(U8X8_CS_PIN, OUTPUT);
 #endif
-  
+
 #ifdef ENABLE_LCD_UI
   setup_ui();
 #else
@@ -313,8 +313,11 @@ void setup()
   master_mixer_r.gain(0, 1.0);
   master_mixer_l.gain(0, 1.0);
 
+#ifdef USE_REVERB
   freeverbs1.roomsize(configuration.reverb_roomsize / 100.0);
   freeverbs1.damping(configuration.reverb_damping / 100.0);
+#endif
+
   master_mixer_r.gain(1, 0.0);
   master_mixer_l.gain(1, 0.0);
 
diff --git a/UI.hpp b/UI.hpp
index 5b73aab..66f983a 100644
--- a/UI.hpp
+++ b/UI.hpp
@@ -146,12 +146,10 @@ void UI_func_engine(uint8_t param);
 void UI_func_information(uint8_t param);
 void UI_func_voice_selection(uint8_t param);
 void UI_func_volume(uint8_t param);
-void UI_func_back(uint8_t param);
-void UI_func_goToRootMenu(uint8_t param);
+void UI_function_not_enabled(void);
 void lcd_display_int(int16_t var, uint8_t size, bool zeros, bool brackets, bool sign);
 void lcd_display_float(float var, uint8_t size_number, uint8_t size_fraction, bool zeros, bool brackets, bool sign);
 
-
 // normal menu
 LCDMenuLib2_menu LCDML_0(255, 0, 0, NULL, NULL); // normal root menu element (do not change)
 LCDMenuLib2 LCDML(LCDML_0, _LCDML_DISP_rows, _LCDML_DISP_cols, lcdml_menu_display, lcdml_menu_clear, lcdml_menu_control);
@@ -206,20 +204,20 @@ uint8_t g_LCDML_CONTROL_prev[NUM_ENCODER] = {0, 0};
 const uint8_t * flipped_scroll_bar[5];
 
 uint8_t * rotTile(const uint8_t * tile) {
-    uint8_t * newt = new uint8_t[8];
-    for (int x = 0; x < 8; x++) {
-        uint8_t newb = 0;
-        for (int y = 0 ; y < 8; y++){
-            newb |= (tile[y] << x) & 0x80;
-            newb >>= 1;
-        }
-        newt[x] = newb;
+  uint8_t * newt = new uint8_t[8];
+  for (int x = 0; x < 8; x++) {
+    uint8_t newb = 0;
+    for (int y = 0 ; y < 8; y++) {
+      newb |= (tile[y] << x) & 0x80;
+      newb >>= 1;
     }
-    return newt;
+    newt[x] = newb;
+  }
+  return newt;
 }
-#endif 
+#endif
 
-void setup_ui(void){
+void setup_ui(void) {
   // LCD Begin
 #ifdef I2C_DISPLAY
   lcd.init();
@@ -245,13 +243,13 @@ void setup_ui(void){
   lcd.createChar(2, (uint8_t*)scroll_bar[2]);
   lcd.createChar(3, (uint8_t*)scroll_bar[3]);
   lcd.createChar(4, (uint8_t*)scroll_bar[4]);
-#else 
-  for (int x=0; x < 5; x++) {
-     flipped_scroll_bar[x] = rotTile(scroll_bar[x]);
+#else
+  for (int x = 0; x < 5; x++) {
+    flipped_scroll_bar[x] = rotTile(scroll_bar[x]);
   }
 #endif
 
-// LCDMenuLib Setup
+  // LCDMenuLib Setup
   LCDML_setup(_LCDML_DISP_cnt);
   // Enable Menu Rollover
   //LCDML.MENU_enRollover();
@@ -458,7 +456,7 @@ void encoder_right_up(void)
           change_disp_sd(true);
 #endif
           eeprom_write();
-          
+
       }
       UI_func_voice_selection(0);
       break;
@@ -698,9 +696,9 @@ void lcdml_menu_display(void)
 #ifdef I2C_DISPLAY
           lcd.setCursor((_LCDML_DISP_cols - 1), n);
           lcd.write((uint8_t)0);
-#else 
+#else
           lcd.drawTile((_LCDML_DISP_cols - 1), n, 1, flipped_scroll_bar[0]);
-          lcd.setCursor((_LCDML_DISP_cols), n+1);
+          lcd.setCursor((_LCDML_DISP_cols), n + 1);
 #endif
         }
         else {
@@ -719,27 +717,27 @@ void lcdml_menu_display(void)
 #ifdef I2C_DISPLAY
           lcd.setCursor((_LCDML_DISP_cols - 1), 0);
           lcd.write((uint8_t)1);
-#else 
+#else
           lcd.drawTile((_LCDML_DISP_cols - 1), 0, 1, flipped_scroll_bar[1]);
           lcd.setCursor((_LCDML_DISP_cols), 1);
-#endif       
+#endif
         } else if (scrollbar_cur_pos == (scrollbar_max - 1)) {
           // max pos
 #ifdef I2C_DISPLAY
           lcd.setCursor((_LCDML_DISP_cols - 1), (n_max - 1));
           lcd.write((uint8_t)4);
-#else 
+#else
           lcd.drawTile((_LCDML_DISP_cols - 1), (n_max - 1), 1, flipped_scroll_bar[4]);
           lcd.setCursor((_LCDML_DISP_cols), (n_max));
-#endif       
+#endif
         } else {
           // between
 #ifdef I2C_DISPLAY
           lcd.setCursor((_LCDML_DISP_cols - 1), scroll_pos / n_max);
           lcd.write((uint8_t)(scroll_pos % n_max) + 1);
-#else 
+#else
           lcd.drawTile((_LCDML_DISP_cols - 1), scroll_pos / n_max, 1, flipped_scroll_bar[(scroll_pos % n_max) + 1]);
-          lcd.setCursor((_LCDML_DISP_cols), (scroll_pos / n_max)+1);
+          lcd.setCursor((_LCDML_DISP_cols), (scroll_pos / n_max) + 1);
 #endif
         }
       }
@@ -777,6 +775,7 @@ void UI_func_sound(uint8_t param)
 
 void UI_func_reverb_roomsize(uint8_t param)
 {
+#ifdef USE_REVERB
   if (LCDML.FUNC_setup())         // ****** SETUP *********
   {
     // setup function
@@ -816,10 +815,14 @@ void UI_func_reverb_roomsize(uint8_t param)
     // you can here reset some global vars or do nothing
     eeprom_write();
   }
+#else
+  UI_function_not_enabled();
+#endif
 }
 
 void UI_func_reverb_damping(uint8_t param)
 {
+#ifdef USE_REVERB
   if (LCDML.FUNC_setup())         // ****** SETUP *********
   {
     // setup function
@@ -859,10 +862,14 @@ void UI_func_reverb_damping(uint8_t param)
     // you can here reset some global vars or do nothing
     eeprom_write();
   }
+#else
+  UI_function_not_enabled();
+#endif
 }
 
 void UI_func_reverb_level(uint8_t param)
 {
+#ifdef USE_REVERB
   if (LCDML.FUNC_setup())         // ****** SETUP *********
   {
     // setup function
@@ -904,6 +911,9 @@ void UI_func_reverb_level(uint8_t param)
     // you can here reset some global vars or do nothing
     eeprom_write();
   }
+#else
+  UI_function_not_enabled();
+#endif
 }
 
 void UI_func_chorus_frequency(uint8_t param)
@@ -1677,7 +1687,7 @@ void UI_func_voice_selection(uint8_t param)
       break;
   }
   for (int x = 2; x < LCD_rows; x++) {
-      lcd.show(x, 0, LCD_cols+1, " ");
+    lcd.show(x, 0, LCD_cols + 1, " ");
   }
 }
 
@@ -1706,12 +1716,37 @@ void UI_func_volume(uint8_t param)
   lcd.show(1, 15, 1, "]");
 }
 
+void UI_function_not_enabled(void)
+{
+  if (LCDML.FUNC_setup())         // ****** SETUP *********
+  {
+    // setup function
+    lcd.setCursor(0, 0);
+    lcd.print(F("Function not"));
+    lcd.setCursor(0, 1);
+    lcd.print(F("enabled!"));
+  }
+
+  if (LCDML.FUNC_loop())          // ****** LOOP *********
+  {
+    if (LCDML.BT_checkEnter())
+    {
+      LCDML.FUNC_goBackToMenu();
+    }
+  }
+
+  if (LCDML.FUNC_close())     // ****** STABLE END *********
+  {
+    // you can here reset some global vars or do nothing
+  }
+}
+
 void lcd_display_int(int16_t var, uint8_t size, bool zeros, bool brackets, bool sign)
 {
   int16_t tmp = 0;
   uint16_t p;
-  bool non_zero_found=false;
-  
+  bool non_zero_found = false;
+
   if (size < 1)
     return;
 
@@ -1736,6 +1771,7 @@ void lcd_display_int(int16_t var, uint8_t size, bool zeros, bool brackets, bool
   {
     p = int(pow(10, i));
     tmp = int(var / p);
+
     if (tmp == 0)
     {
       if (zeros == true)
@@ -1773,7 +1809,15 @@ void lcd_display_float(float var, uint8_t size_number, uint8_t size_fraction, bo
   if (brackets == true)
     lcd.print(F("["));
 
-  lcd_display_int(int(number), size_number, zeros, false, sign);
+  if (int(number) == 0)
+  {
+    if (zeros == true)
+      lcd.print(F("00"));
+    else
+      lcd.print(F(" 0"));
+  }
+  else
+    lcd_display_int(int(number), size_number, zeros, false, sign);
   lcd.print(F("."));
   lcd_display_int(round(fraction * pow(10, size_fraction)), size_fraction, true, false, false);
 
diff --git a/config.h b/config.h
index 224070c..12869bf 100644
--- a/config.h
+++ b/config.h
@@ -31,33 +31,29 @@
 
 // ATTENTION! For better latency you have to redefine AUDIO_BLOCK_SAMPLES from
 // 128 to 64 in <ARDUINO-IDE-DIR>/cores/teensy3/AudioStream.h
-#define AUDIO_BLOCK_SAMPLES 64
 
 // If you want to test the system with Linux and withous any keyboard and/or audio equipment, you can do the following:
 // 1. In Arduino-IDE enable "Tools->USB-Type->Serial + MIDI + Audio"
 // 2. Build the firmware with "MIDI_DEVICE_USB" enabled in config.h.
-// 3. Afterconnecting to a Linux system there should be a MIDI an audio device available that is called "MicroMDAEPiano", so you can start the following:
+// 3. Afterconnecting to a Linux system there should be a MIDI an audio device available that is called "MicroMDexed", so you can start the following:
 // $ aplaymidi -p 20:0 <MIDI-File> # e.g. test.mid
 // $ arecord -f cd -Dhw:1,0 /tmp/bla.wav
 
-
-#define VERSION "0.9.7"
+#define VERSION "0.9.8"
 
 //*************************************************************************************************
 //* DEVICE SETTINGS
 //*************************************************************************************************
 
 // MIDI
-#define MIDI_DEVICE_DIN Serial1
-//#define AUDIO_DEVICE_USB
-//#define MIDI_DEVICE_USB 1
-//#define MIDI_DEVICE_USB_HOST 1
-//#define MIDI_DEVICE_NUMBER 0
+//#define MIDI_DEVICE_DIN Serial1
+#define MIDI_DEVICE_USB 1
+#define MIDI_DEVICE_USB_HOST 1
 
 // AUDIO
 // If nothing is defined Teensy internal DAC is used as audio output device!
 // Left and right channel audio signal is presented on pins A21 and A22.
-//#define AUDIO_DEVICE_USB
+#define AUDIO_DEVICE_USB
 //#define TEENSY_DAC
 //#define TEENSY_DAC_SYMMETRIC
 //#define TEENSY_AUDIO_BOARD
@@ -84,13 +80,12 @@
 #define MOD_WAVEFORM WAVEFORM_TRIANGLE // WAVEFORM_SINE WAVEFORM_TRIANGLE WAVEFORM_SAWTOOTH WAVEFORM_SAWTOOTH_REVERSE
 #define MOD_FILTER_OUTPUT MOD_LINKWITZ_RILEY_FILTER_OUTPUT // MOD_LINKWITZ_RILEY_FILTER_OUTPUT MOD_BUTTERWORTH_FILTER_OUTPUT MOD_NO_FILTER_OUTPUT
 #define MOD_FILTER_CUTOFF_HZ 3000
-#define USE_REVERB 1
+//#define USE_REVERB 1
 
 //*************************************************************************************************
 //* AUDIO SETTINGS
 //*************************************************************************************************
 // https://rechneronline.de/funktionsgraphen/
-#define VOLUME_CURVE 0.07
 #ifndef TEENSY_AUDIO_BOARD
 #if AUDIO_BLOCK_SAMPLES == 64
 #define AUDIO_MEM 450
@@ -100,6 +95,7 @@
 #define DELAY_MAX_TIME 600
 #define REDUCE_LOUDNESS 1
 #else
+#define SGTL5000_LINEOUT_LEVEL 29
 #if AUDIO_BLOCK_SAMPLES == 64
 #define AUDIO_MEM 900
 #else
@@ -118,7 +114,6 @@
 #define STANDARD_LCD_I2C
 //#define OLED_SPI
 
-
 // LCD Display
 //I2C_DISPLAY only
 #ifdef STANDARD_LCD_I2C
@@ -167,20 +162,19 @@
 #define TEENSY4
 #endif
 
-// Teensy Audio Shield:
+// Teensy Audio Shield (not used)
 //#define SDCARD_CS_PIN    10
 //#define SDCARD_MOSI_PIN  7
 //#define SDCARD_SCK_PIN   14
-#define SGTL5000_LINEOUT_LEVEL 29
 #ifndef TEENSY4
 // Teensy 3.5 & 3.6 SD card
 #define SDCARD_CS_PIN    BUILTIN_SDCARD
-#define SDCARD_MOSI_PIN  11  // not actually used
-#define SDCARD_SCK_PIN   13  // not actually used
+#define SDCARD_MOSI_PIN  11
+#define SDCARD_SCK_PIN   13
 #else
 #define SDCARD_CS_PIN    10
-#define SDCARD_MOSI_PIN  11  // not actually used
-#define SDCARD_SCK_PIN   13  // not actually used
+#define SDCARD_MOSI_PIN  11
+#define SDCARD_SCK_PIN   13
 #endif
 
 // Encoder with button
@@ -201,8 +195,6 @@
 #define BUT_DEBOUNCE_MS 20
 #define LONG_BUTTON_PRESS 500
 
-
-
 // Internal timer
 #define AUTOSTORE_MS 5000
 #define VOICE_SELECTION_MS 2000
diff --git a/effect_stereo_mono.h b/effect_stereo_mono.h
index 0379326..f9b39f9 100644
--- a/effect_stereo_mono.h
+++ b/effect_stereo_mono.h
@@ -37,7 +37,7 @@ class AudioEffectStereoMono : public AudioStream
     AudioEffectStereoMono(void):
       AudioStream(2, inputQueueArray)
     {
-      _enabled = false;
+      _enabled = true;
     }
 
     virtual void update(void);