diff --git a/sw_usb_audio/app_usb_aud_fosi_c1/src/extensions/audiohw.xc b/sw_usb_audio/app_usb_aud_fosi_c1/src/extensions/audiohw.xc
index 264b3a9..941f414 100644
--- a/sw_usb_audio/app_usb_aud_fosi_c1/src/extensions/audiohw.xc
+++ b/sw_usb_audio/app_usb_aud_fosi_c1/src/extensions/audiohw.xc
@@ -48,7 +48,7 @@ unsigned g_unmute_dac_state, g_unmute_time,  g_format_time;
 unsigned g_volume_level = 60, g_saved_volume_level = 60;
 unsigned g_request_volume_set = 0;
 unsigned g_dac_vol = 0xB8;
-unsigned g_adc_vol = 0x25;
+unsigned g_adc_vol = 0x18;
 // 改动原因：CODEC 在 AudioHwRemote2 内完成初始化后置 1，供其它逻辑确认 NAU88 已就绪。
 unsigned g_codec_init_done = 0;
 unsigned g_adc_loop = 0;
@@ -265,7 +265,7 @@ void switch_mode_by_c1_mode(unsigned c1_mode, unsigned force_reboot)
 
 #define NAU88L21_PGA_GAIN_REG_MIN_USED_VALUE 0x0    // 0x1=1, 0dB (0x0, -1dB which is not used in this design)
 #define NAU88L21_PGA_GAIN_REG_MAX_VALUE 0x25+1    // 0x25=37, 36dB. +1 is for extra 1.5dB digital gain
-#define NAU88L21_PGA_GAIN_REG_DEFAULT_VALUE (NAU88L21_PGA_GAIN_REG_MAX_VALUE)
+#define NAU88L21_PGA_GAIN_REG_DEFAULT_VALUE (24)
 
 // 改动原因：4E 为耳机/MIC 检测输入（读 bit2/bit3），原先声明为 out 无法采样；改为 in port 与硬件方向一致。
 on tile[0]: in port p_mic_phone_detect     =  XS1_PORT_4E;
diff --git a/sw_usb_audio/app_usb_aud_fosi_c1_lp/src/extensions/audiohw.xc b/sw_usb_audio/app_usb_aud_fosi_c1_lp/src/extensions/audiohw.xc
index 6d73b49..272a364 100644
--- a/sw_usb_audio/app_usb_aud_fosi_c1_lp/src/extensions/audiohw.xc
+++ b/sw_usb_audio/app_usb_aud_fosi_c1_lp/src/extensions/audiohw.xc
@@ -48,7 +48,7 @@ unsigned g_unmute_dac_state, g_unmute_time,  g_format_time;
 unsigned g_volume_level = 60, g_saved_volume_level = 60;
 unsigned g_request_volume_set = 0;
 unsigned g_dac_vol = 0xB8;
-unsigned g_adc_vol = 0x25;
+unsigned g_adc_vol = 0x18;
 // 改动原因：CODEC 在 AudioHwRemote2 内完成初始化后置 1，供其它逻辑确认 NAU88 已就绪。
 unsigned g_codec_init_done = 0;
 unsigned g_adc_loop = 0;
@@ -265,7 +265,7 @@ void switch_mode_by_c1_mode(unsigned c1_mode, unsigned force_reboot)
 
 #define NAU88L21_PGA_GAIN_REG_MIN_USED_VALUE 0x0    // 0x1=1, 0dB (0x0, -1dB which is not used in this design)
 #define NAU88L21_PGA_GAIN_REG_MAX_VALUE 0x25+1    // 0x25=37, 36dB. +1 is for extra 1.5dB digital gain
-#define NAU88L21_PGA_GAIN_REG_DEFAULT_VALUE (NAU88L21_PGA_GAIN_REG_MAX_VALUE)
+#define NAU88L21_PGA_GAIN_REG_DEFAULT_VALUE (24)
 
 // 改动原因：4E 为耳机/MIC 检测输入（读 bit2/bit3），原先声明为 out 无法采样；改为 in port 与硬件方向一致。
 on tile[0]: in port p_mic_phone_detect     =  XS1_PORT_4E;