reading 512k works, but hangs the cpu when trying to play 5 samples

soundcube-firmware/soundcube-firmware.ino

@@ -353,7 +353,7 @@ Vibration vibration;
 // -------------------------------------------- SETUP 0
 
 void setup() {
-  i2s.setSysClk(48000);
+  //i2s.setSysClk(48000);
 
   delay(500);
   
@@ -770,9 +770,9 @@ void loop(){
     }
 
     if(streams_loaded) {
-//      for(int i = 0; i < NSTREAMS; i++){
-        stream[streamcnt].stream();
-//      }
+      for(int i = 0; i < NSTREAMS; i++){
+        stream[i].streamChunk();
+      }
     }
     streamcnt = (streamcnt + 1) % 16;
 

soundcube-firmware/wavestream.h

@@ -106,18 +106,20 @@ struct WaveFile{
     return true;
   }
 
-  bool readblockDMA128(){
+  bool readblockSD(){
     void *bufferStart = buffer.getWritePointer();
-    
-    remains = min(buffer.remains(), 128);
-    adv = file.readBytes((char*)bufferStart, remains);
-	  buffer.advance(adv);
+    remains = buffer.remains();
 
-    if(!file.available() && loop) file.seek(44, SeekSet);
-    if(!file.available() && !loop) {
-      file.seek(44, SeekSet);
-      return false;
-    }    
+    if(remains > 512){
+      adv = file.readBytes((char*)bufferStart, 512);
+      buffer.advance(adv);
+
+      if(!file.available() && loop) file.seek(44, SeekSet);
+      if(!file.available() && !loop) {
+        file.seek(44, SeekSet);
+        return false;
+      }    
+    }
     return true;
   }
 
@@ -186,7 +188,7 @@ class WaveStream{
 
     void streamChunk(){
       if(!wavefile.buffer.isFull()){
-        bool ok = wavefile.readblockDMA128();
+        bool ok = wavefile.readblockSD();
         if(!ok) playing = false;
       }
     }