diff --git a/NOTES.txt b/NOTES.txt
index 7bcacbc..764e42f 100644
--- a/NOTES.txt
+++ b/NOTES.txt
@@ -200,7 +200,11 @@ Radio4 reception improves from very bad to almost good.
 
 However, strong stations (radio3) sound slightly worse with the DIY antenna
 than with the basic DVB antenna.
-May be caused by clipping due to too strong signal from antenna.
+Theory: Distortion caused by clipping I/Q samples due to strong antenna signal.
+No, that's not it. Reducing LNA gain or IF gain does not help much;
+small DVB antenna still sounds better than DIY antenna.
+Difference only clear in stereo mode.
+Don't know what's going on here, maybe the DIY antenna is just not good.
 
 
 Local radio stations
diff --git a/TODO.txt b/TODO.txt
index 3b2b5b9..9b7de9e 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -1,5 +1,3 @@
-* (quality) solve issues with bad sound due to strong antenna signal
-            (experiment with adaptive LNA gain or adaptive IF gain)
 * (speedup) maybe replace high-order FIR downsampling filter with 2nd order butterworth followed by lower order FIR filter
 * (feature) implement RDS decoding
 * (quality) consider FM demodulation with PLL instead of phase discriminator