diff --git a/@postman/src/main.cpp b/@postman/src/main.cpp
index cbf2254..0a0399c 100644
--- a/@postman/src/main.cpp
+++ b/@postman/src/main.cpp
@@ -57,8 +57,9 @@
 //
 #define HAVE_CLIENT_I2C
 #define DISABLE_AP
-#define REPLICATE_NOTE_REQ
-#define USE_ALTERNATIVE_ADDRESSES
+// #define SERIAL_SWAP
+// #define REPLICATE_NOTE_REQ
+// #define USE_ALTERNATIVE_ADDRESSES
 
 //============<parameters>============
 //
@@ -344,33 +345,37 @@ void setup() {
   esp_now_register_send_cb(onDataSent);
   esp_now_register_recv_cb(onDataReceive);
   //
-  // Serial.println("- ! (esp_now_add_peer) ==> add a 'broadcast peer' (FF:FF:FF:FF:FF:FF).");
-  // uint8_t broadcastmac[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
-  //
-  // //
+  Serial.println("- ! (esp_now_add_peer) ==> add a 'broadcast peer' (FF:FF:FF:FF:FF:FF).");
+  uint8_t broadcastmac[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+
+  // option 1-1)) broadcast to all. for ESP8266
+  esp_now_add_peer(broadcastmac, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
+
+  // // option 1-2)) broadcast to all. for ESP32
   // esp_now_peer_info_t peerInfo;
   // memcpy(peerInfo.peer_addr, broadcastmac, 6);
   // peerInfo.channel = 0;
   // peerInfo.encrypt = false;
   // esp_now_add_peer(&peerInfo);
 
-#if defined(USE_ALTERNATIVE_ADDRESSES)
-  AddressBook * book = lib.getBookByTitle("audioooo alt");
-#else
-  AddressBook * book = lib.getBookByTitle("audioooo");
-#endif
-  for (int idx = 0; idx < book->list.size(); idx++) {
-    Serial.println("- ! (esp_now_add_peer) ==> add a '" + book->list[idx].name + "'.");
-#if defined(ESP32)
-    esp_now_peer_info_t peerInfo;
-    memcpy(peerInfo.peer_addr, book->list[idx].mac, 6);
-    peerInfo.channel = 0;
-    peerInfo.encrypt = false;
-    esp_now_add_peer(&peerInfo);
-#else
-    esp_now_add_peer(book->list[idx].mac, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
-#endif
-  }
+//   // option 2)) according to the addressbook.
+// #if defined(USE_ALTERNATIVE_ADDRESSES)
+//   AddressBook * book = lib.getBookByTitle("audioooo alt");
+// #else
+//   AddressBook * book = lib.getBookByTitle("audioooo");
+// #endif
+//   for (int idx = 0; idx < book->list.size(); idx++) {
+//     Serial.println("- ! (esp_now_add_peer) ==> add a '" + book->list[idx].name + "'.");
+// #if defined(ESP32)
+//     esp_now_peer_info_t peerInfo;
+//     memcpy(peerInfo.peer_addr, book->list[idx].mac, 6);
+//     peerInfo.channel = 0;
+//     peerInfo.encrypt = false;
+//     esp_now_add_peer(&peerInfo);
+// #else
+//     esp_now_add_peer(book->list[idx].mac, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
+// #endif
+//   }
   //
   Serial.println("-");
   Serial.println("\".-.-.-. :)\"");
diff --git a/@sampler/src/main.cpp b/@sampler/src/main.cpp
index 5a06750..7bfa9e2 100644
--- a/@sampler/src/main.cpp
+++ b/@sampler/src/main.cpp
@@ -16,6 +16,8 @@
 #define IDLE_FREQ 22000
 #define IDLE_AMP 0 // --> creative muvo 2 doesn't need this. they just stay on!
 
+#define GAIN_MAX 1.0 // if 1.0 is too loud, give max. limit here.
+
 //teensy audio
 #include <Audio.h>
 // #include <SPI.h>
@@ -163,19 +165,19 @@ void receiveEvent(int numBytes) {
     int velocity = str_velocity.toInt();   // 0 ~ 127
     float amp_gain = (float)velocity / 127.0;
     //
-    amp_gain = amp_gain * 0.3; // 1.0 was too loud. => 0.3 max.
+    amp_gain = amp_gain * GAIN_MAX;
     //
     amp1.gain(amp_gain);
     amp2.gain(amp_gain);
     //
     int gate = str_gate.toInt();
     if (gate == 0) {
-      // filter out re-triggering same note while it is playing.
-      if (!playSdWav1.isPlaying() || sample_now != key) {
-        sample_now = key;
-        sample_player_stop_task.restart();
-        Serial.println("sample_player_stop_task");
-      }
+      // filter out re-triggering same note while it is playing. <== ???? WORKS????
+      // if (!playSdWav1.isPlaying() || sample_now != key) { <== ???? WORKS????
+      sample_now = key;
+      sample_player_stop_task.restart();
+      Serial.println("sample_player_stop_task");
+      // }
     } else {
       sample_now = key;
       sample_player_start_task.restart();
@@ -259,8 +261,8 @@ void setup() {
   mixer2.gain(1,1.0);
   mixer2.gain(2,0);
   mixer2.gain(3,0);
-  amp1.gain(0.3); // 1.0 was too loud. => 0.3
-  amp2.gain(0.3);
+  amp1.gain(GAIN_MAX);
+  amp2.gain(GAIN_MAX);
 
   //let auto-poweroff speakers stay turned ON!
   sine1.frequency(IDLE_FREQ);