diff --git a/sync_audio_test.py b/sync_audio_test.py
index d8c5503..adce8de 100644
--- a/sync_audio_test.py
+++ b/sync_audio_test.py
@@ -166,24 +166,34 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.gw = pg.GraphicsLayoutWidget()
         lay.addWidget(self.gw, stretch=1)
 
+        # overlay: A and B on same axes
+        self.p0 = self.gw.addPlot(row=0, col=0, title="Overlay A (teal) + B (red)")
+        self.p0.showGrid(x=True, y=True)
+        self.p0.setLabel("bottom", "Time", "s")
+        self.curve_a_ov = self.p0.plot(self.t_a, self.a_plot, pen=pg.mkPen("#4cc9f0", width=1), name="A")
+        self.curve_b_ov = self.p0.plot(self.t_b, self.b_plot, pen=pg.mkPen("#f72585", width=1, style=QtCore.Qt.PenStyle.DashLine), name="B")
+        self.p0.addLegend(offset=(60, 10))
+        self.p0.setMouseEnabled(x=True, y=False)
+
         # waveform A
-        self.p1 = self.gw.addPlot(row=0, col=0, title="Waveform A (reference)")
+        self.p1 = self.gw.addPlot(row=1, col=0, title="Waveform A (reference)")
         self.p1.showGrid(x=True, y=True)
         self.p1.setLabel("bottom", "Time", "s")
         self.curve_a = self.p1.plot(self.t_a, self.a_plot, pen=pg.mkPen("#4cc9f0", width=1))
         self.p1.setMouseEnabled(x=True, y=False)
 
         # waveform B with lag
-        self.p2 = self.gw.addPlot(row=1, col=0, title=f"Waveform B (shifted by lag)")
+        self.p2 = self.gw.addPlot(row=2, col=0, title=f"Waveform B (shifted by lag)")
         self.p2.showGrid(x=True, y=True)
         self.p2.setLabel("bottom", "Time", "s")
         self.curve_b = self.p2.plot(self.t_b, self.b_plot, pen=pg.mkPen("#f72585", width=1))
         self.p2.setMouseEnabled(x=True, y=False)
         # link x
-        self.p2.setXLink(self.p1)
+        self.p1.setXLink(self.p0)
+        self.p2.setXLink(self.p0)
 
         # xcorr
-        self.p3 = self.gw.addPlot(row=2, col=0, title="Cross-correlation (GCC-PHAT)" if method=="phat" else "Cross-correlation")
+        self.p3 = self.gw.addPlot(row=3, col=0, title="Cross-correlation (GCC-PHAT)" if method=="phat" else "Cross-correlation")
         self.p3.showGrid(x=True, y=True)
         self.p3.setLabel("bottom", "Lag", "s")
         # decimate corr with peak awareness
@@ -316,11 +326,9 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.spin_samp.blockSignals(True); self.spin_samp.setValue(lag_samp); self.spin_samp.blockSignals(False)
         self.peak_line.setPos(lag_sec)
         # shift B curve visually by lag (pad with silence not needed for visualize, just shift x)
-        # we keep t_b but offset x
         shift = lag_sec
-        # pyqtgraph setPos shifts items; we recreate x
-        # Instead shift data: plot t_b + lag
         self.curve_b.setData(self.t_b + shift, self.b_plot)
+        self.curve_b_ov.setData(self.t_b + shift, self.b_plot)
         self._update_xcorr_label()
         self.update_labels()
         self._updating = False
@@ -375,6 +383,7 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.a_plot, _ = decimate_for_plot(self.a)
         self.b_plot, _ = decimate_for_plot(self.b)
         self.curve_a.setData(self.t_a, self.a_plot)
+        self.curve_a_ov.setData(self.t_a, self.a_plot)
         # recalc
         lag, _, corr = correlate(self.a, self.b, sr=self.sr, method=self.method, device=self.device_pref)
         self.corr = corr