diff --git a/src/dsp/nam_engine_host.py b/src/dsp/nam_engine_host.py
index ad2b5c2..23d7d4e 100644
--- a/src/dsp/nam_engine_host.py
+++ b/src/dsp/nam_engine_host.py
@@ -93,6 +93,19 @@ class FastNAMHost:
             return 0.0
         return self._engine.avg_inference_ms
 
+    @property
+    def block_size(self) -> int:
+        return self._block_size
+
+    def set_block_size(self, block_size: int) -> None:
+        """Update block size. Reloads current model if loaded."""
+        if block_size == self._block_size:
+            return
+        self._block_size = block_size
+        if self._loaded_path:
+            logger.info("Block size changed to %d — reloading model %s", block_size, self._loaded_path)
+            self.load_model(self._loaded_path)
+
     # ── Model loading ──────────────────────────────────────────────
 
     def load_model(self, model_path: str) -> bool:
diff --git a/src/web/server.py b/src/web/server.py
index ffe292e..77b1544 100644
--- a/src/web/server.py
+++ b/src/web/server.py
@@ -1361,6 +1361,10 @@ class WebServer:
             # Restart JACK audio client
             if jack_client:
                 jack_client.start()
+            # Sync NAM engine block size with new period
+            nam_host = self.deps.nam_host
+            if nam_host and hasattr(nam_host, 'set_block_size'):
+                nam_host.set_block_size(profile["period"])
             await self._manager.broadcast({
                 "type": "audio_profile_changed",
                 "profile": profile_key,