diff --git a/test_audio_routing.c b/test_audio_routing.c
index 79b39b3..f7551d6 100644
--- a/test_audio_routing.c
+++ b/test_audio_routing.c
@@ -48,6 +48,11 @@ static float test_audio_input[MAX_CHANNELS][MAX_SAMPLES];
 static atomic_size_t test_audio_input_count[MAX_CHANNELS];
 static atomic_size_t test_audio_input_read[MAX_CHANNELS];
 
+// Debug counters
+static atomic_ulong test_callback_count;
+static atomic_ulong test_midi_sent_count;
+static atomic_ulong test_audio_written_count;
+
 // Shared MIDI buffer (written by test thread, read by JACK callback)
 static uint8_t test_midi_buffer[3];  // status, note, velocity
 static atomic_bool test_midi_pending;
@@ -81,6 +86,8 @@ static int test_process_callback(jack_nframes_t nframes, void *arg) {
     (void)arg;
     if (!atomic_load(&test_running)) return 0;
     
+    atomic_fetch_add(&test_callback_count, 1);
+    
     pthread_mutex_lock(&test_buffer_mutex);
     
     // Write test audio to output ports (to be sent to looper)
@@ -91,14 +98,17 @@ static int test_process_callback(jack_nframes_t nframes, void *arg) {
         size_t read_pos = atomic_load(&test_audio_input_read[ch]);
         size_t count = atomic_load(&test_audio_input_count[ch]);
         
+        bool wrote_audio = false;
         for (jack_nframes_t i = 0; i < nframes; i++) {
             if (read_pos + i < count) {
                 out[i] = test_audio_input[ch][read_pos + i];
+                if (test_audio_input[ch][read_pos + i] != 0.0f) wrote_audio = true;
             } else {
                 out[i] = 0.0f;
             }
         }
         atomic_store(&test_audio_input_read[ch], read_pos + nframes);
+        if (wrote_audio) atomic_fetch_add(&test_audio_written_count, 1);
     }
     
     // Read audio from looper outputs
@@ -269,6 +279,10 @@ static void send_sine_wave(int channel, float frequency, float amplitude, jack_n
     // Wait for the JACK callback to consume the audio
     // (the callback runs in a separate thread)
     usleep(duration * 1000 + 300000);  // duration ms + 300ms extra
+    
+    unsigned long cb_count = atomic_load(&test_callback_count);
+    unsigned long aw_count = atomic_load(&test_audio_written_count);
+    printf("    [DEBUG] Callback count: %lu, Audio written: %lu\n", cb_count, aw_count);
 }
 
 static void send_midi_note(int note, int velocity) {
@@ -282,11 +296,16 @@ static void send_midi_note(int note, int velocity) {
     test_midi_buffer[1] = note & 0x7F;
     test_midi_buffer[2] = velocity & 0x7F;
     atomic_store(&test_midi_pending, true);
+    atomic_fetch_add(&test_midi_sent_count, 1);
     
     pthread_mutex_unlock(&test_buffer_mutex);
     
     // Wait longer for JACK to process the MIDI message
     usleep(300000);  // 300ms to let JACK process
+    
+    unsigned long cb_count = atomic_load(&test_callback_count);
+    unsigned long ms_count = atomic_load(&test_midi_sent_count);
+    printf("    [DEBUG] Callback count: %lu, MIDI sent: %lu\n", cb_count, ms_count);
 }
 
 static float get_channel_rms(int channel) {
@@ -561,6 +580,9 @@ int main(void) {
     atomic_store(&tests_failed, 0);
     atomic_store(&test_running, true);
     atomic_store(&test_timeout, false);
+    atomic_store(&test_callback_count, 0);
+    atomic_store(&test_midi_sent_count, 0);
+    atomic_store(&test_audio_written_count, 0);
     
     // Start watchdog thread
     pthread_t watchdog;