diff --git a/modules/audio_processing/test/aec_dump_based_simulator.cc b/modules/audio_processing/test/aec_dump_based_simulator.cc
index a0106dc679..0852fe0121 100644
--- a/modules/audio_processing/test/aec_dump_based_simulator.cc
+++ b/modules/audio_processing/test/aec_dump_based_simulator.cc
@@ -15,7 +15,6 @@
 #include "modules/audio_processing/echo_control_mobile_impl.h"
 #include "modules/audio_processing/test/aec_dump_based_simulator.h"
 #include "modules/audio_processing/test/protobuf_utils.h"
-#include "modules/audio_processing/test/runtime_setting_util.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/numerics/safe_conversions.h"
@@ -448,8 +447,10 @@ void AecDumpBasedSimulator::HandleMessage(
                               ? *settings_.use_pre_amplifier
                               : msg.pre_amplifier_enabled();
       apm_config.pre_amplifier.enabled = enable;
-      apm_config.pre_amplifier.fixed_gain_factor =
-          settings_.pre_amplifier_gain_factor;
+      if (settings_.pre_amplifier_gain_factor) {
+        apm_config.pre_amplifier.fixed_gain_factor =
+            *settings_.pre_amplifier_gain_factor;
+      }
     }
 
     if (settings_.use_verbose_logging && msg.has_experiments_description() &&
@@ -549,7 +550,13 @@ void AecDumpBasedSimulator::HandleMessage(
 void AecDumpBasedSimulator::HandleMessage(
     const webrtc::audioproc::RuntimeSetting& msg) {
   RTC_CHECK(ap_.get());
-  ReplayRuntimeSetting(ap_.get(), msg);
+  // Handle capture pre-gain runtime setting only if not overridden.
+  if ((!settings_.use_pre_amplifier || !(*settings_.use_pre_amplifier)) &&
+      !settings_.pre_amplifier_gain_factor) {
+    ap_->SetRuntimeSetting(
+        AudioProcessing::RuntimeSetting::CreateCapturePreGain(
+            msg.capture_pre_gain()));
+  }
 }
 
 void AecDumpBasedSimulator::MaybeOpenCallOrderFile() {
diff --git a/modules/audio_processing/test/audio_processing_simulator.cc b/modules/audio_processing/test/audio_processing_simulator.cc
index 0d57749fd4..277b1b3b53 100644
--- a/modules/audio_processing/test/audio_processing_simulator.cc
+++ b/modules/audio_processing/test/audio_processing_simulator.cc
@@ -384,8 +384,10 @@ void AudioProcessingSimulator::CreateAudioProcessor() {
   }
   if (settings_.use_pre_amplifier) {
     apm_config.pre_amplifier.enabled = *settings_.use_pre_amplifier;
-    apm_config.pre_amplifier.fixed_gain_factor =
-        settings_.pre_amplifier_gain_factor;
+    if (settings_.pre_amplifier_gain_factor) {
+      apm_config.pre_amplifier.fixed_gain_factor =
+          *settings_.pre_amplifier_gain_factor;
+    }
   }
 
   const bool use_legacy_aec = settings_.use_aec && *settings_.use_aec &&
diff --git a/modules/audio_processing/test/audio_processing_simulator.h b/modules/audio_processing/test/audio_processing_simulator.h
index 2ff2539f89..60ee6ea4b4 100644
--- a/modules/audio_processing/test/audio_processing_simulator.h
+++ b/modules/audio_processing/test/audio_processing_simulator.h
@@ -78,7 +78,7 @@ struct SimulationSettings {
   float agc2_fixed_gain_db;
   AudioProcessing::Config::GainController2::LevelEstimator
       agc2_adaptive_level_estimator;
-  float pre_amplifier_gain_factor;
+  absl::optional<float> pre_amplifier_gain_factor;
   absl::optional<int> vad_likelihood;
   absl::optional<int> ns_level;
   absl::optional<bool> use_refined_adaptive_filter;
diff --git a/modules/audio_processing/test/audioproc_float_impl.cc b/modules/audio_processing/test/audioproc_float_impl.cc
index d29541b41b..f9cefce77a 100644
--- a/modules/audio_processing/test/audioproc_float_impl.cc
+++ b/modules/audio_processing/test/audioproc_float_impl.cc
@@ -163,7 +163,7 @@ WEBRTC_DEFINE_string(
     "AGC2 adaptive digital level estimator to use [RMS, peak]");
 
 WEBRTC_DEFINE_float(pre_amplifier_gain_factor,
-                    1.f,
+                    kParameterNotSpecifiedValue,
                     "Pre-amplifier gain factor (linear) to apply");
 WEBRTC_DEFINE_int(vad_likelihood,
                   kParameterNotSpecifiedValue,
@@ -241,6 +241,14 @@ void SetSettingIfSpecified(int value, absl::optional<int>* parameter) {
   }
 }
 
+void SetSettingIfSpecified(float value, absl::optional<float>* parameter) {
+  constexpr float kFloatParameterNotSpecifiedValue =
+      kParameterNotSpecifiedValue;
+  if (value != kFloatParameterNotSpecifiedValue) {
+    *parameter = value;
+  }
+}
+
 void SetSettingIfFlagSet(int32_t flag, absl::optional<bool>* parameter) {
   if (flag == 0) {
     *parameter = false;
@@ -339,7 +347,8 @@ SimulationSettings CreateSettings() {
   settings.agc2_fixed_gain_db = FLAG_agc2_fixed_gain_db;
   settings.agc2_adaptive_level_estimator =
       MapAgc2AdaptiveLevelEstimator(FLAG_agc2_adaptive_level_estimator);
-  settings.pre_amplifier_gain_factor = FLAG_pre_amplifier_gain_factor;
+  SetSettingIfSpecified(FLAG_pre_amplifier_gain_factor,
+                        &settings.pre_amplifier_gain_factor);
   SetSettingIfSpecified(FLAG_vad_likelihood, &settings.vad_likelihood);
   SetSettingIfSpecified(FLAG_ns_level, &settings.ns_level);
   SetSettingIfSpecified(FLAG_stream_delay, &settings.stream_delay);
@@ -531,6 +540,12 @@ void PerformBasicParameterSanityChecks(const SimulationSettings& settings) {
       !settings.aec_dump_input_filename &&
           settings.call_order_output_filename.has_value(),
       "Error: --output_custom_call_order_file needs an AEC dump input file.\n");
+
+  ReportConditionalErrorAndExit(
+      (!settings.use_pre_amplifier || !(*settings.use_pre_amplifier)) &&
+          settings.pre_amplifier_gain_factor.has_value(),
+      "Error: --pre_amplifier_gain_factor needs --pre_amplifier to be "
+      "specified and set.\n");
 }
 
 }  // namespace