diff --git a/src/core/analog_controller.cpp b/src/core/analog_controller.cpp
index 7ab401652..5f28482be 100644
--- a/src/core/analog_controller.cpp
+++ b/src/core/analog_controller.cpp
@@ -894,7 +894,7 @@ const Controller::ControllerInfo AnalogController::INFO = {ControllerType::Analo
                                                            s_settings,
                                                            Controller::VibrationCapabilities::LargeSmallMotors};
 
-void AnalogController::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void AnalogController::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
   m_force_analog_on_reset = si.GetBoolValue(section, "ForceAnalogOnReset", true);
diff --git a/src/core/analog_controller.h b/src/core/analog_controller.h
index eb6ceaea3..b1a9a117d 100644
--- a/src/core/analog_controller.h
+++ b/src/core/analog_controller.h
@@ -80,7 +80,7 @@ public:
   void ResetTransferState() override;
   bool Transfer(const u8 data_in, u8* data_out) override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
 private:
   using MotorState = std::array<u8, NUM_MOTORS>;
diff --git a/src/core/analog_joystick.cpp b/src/core/analog_joystick.cpp
index 4334a2b1e..4b545180b 100644
--- a/src/core/analog_joystick.cpp
+++ b/src/core/analog_joystick.cpp
@@ -414,7 +414,7 @@ const Controller::ControllerInfo AnalogJoystick::INFO = {ControllerType::AnalogJ
                                                          s_settings,
                                                          Controller::VibrationCapabilities::NoVibration};
 
-void AnalogJoystick::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void AnalogJoystick::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
   m_analog_deadzone = std::clamp(si.GetFloatValue(section, "AnalogDeadzone", DEFAULT_STICK_DEADZONE), 0.0f, 1.0f);
diff --git a/src/core/analog_joystick.h b/src/core/analog_joystick.h
index a7953a5b2..e9472d4c2 100644
--- a/src/core/analog_joystick.h
+++ b/src/core/analog_joystick.h
@@ -77,7 +77,7 @@ public:
   void ResetTransferState() override;
   bool Transfer(const u8 data_in, u8* data_out) override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
 private:
   enum class TransferState : u8
diff --git a/src/core/controller.cpp b/src/core/controller.cpp
index d10b102c4..1fdfbc47a 100644
--- a/src/core/controller.cpp
+++ b/src/core/controller.cpp
@@ -106,7 +106,7 @@ u32 Controller::GetInputOverlayIconColor() const
   return 0xFFFFFFFFu;
 }
 
-void Controller::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void Controller::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
 }
 
diff --git a/src/core/controller.h b/src/core/controller.h
index 91b9a7ea5..bf2bc766d 100644
--- a/src/core/controller.h
+++ b/src/core/controller.h
@@ -97,7 +97,7 @@ public:
   virtual u32 GetInputOverlayIconColor() const;
 
   /// Loads/refreshes any per-controller settings.
-  virtual void LoadSettings(SettingsInterface& si, const char* section, bool initial);
+  virtual void LoadSettings(const SettingsInterface& si, const char* section, bool initial);
 
   /// Creates a new controller of the specified type.
   static std::unique_ptr<Controller> Create(ControllerType type, u32 index);
diff --git a/src/core/guncon.cpp b/src/core/guncon.cpp
index e2f0c8fc7..a6da13dd5 100644
--- a/src/core/guncon.cpp
+++ b/src/core/guncon.cpp
@@ -307,7 +307,7 @@ const Controller::ControllerInfo GunCon::INFO = {
   ControllerType::GunCon, "GunCon",   TRANSLATE_NOOP("ControllerType", "GunCon"),    ICON_PF_LIGHT_GUN,
   s_binding_info,         s_settings, Controller::VibrationCapabilities::NoVibration};
 
-void GunCon::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void GunCon::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
 
diff --git a/src/core/guncon.h b/src/core/guncon.h
index 1b5292acf..1e3ec0b36 100644
--- a/src/core/guncon.h
+++ b/src/core/guncon.h
@@ -37,7 +37,7 @@ public:
   void Reset() override;
   bool DoState(StateWrapper& sw, bool apply_input_state) override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
   float GetBindState(u32 index) const override;
   void SetBindState(u32 index, float value) override;
diff --git a/src/core/justifier.cpp b/src/core/justifier.cpp
index 4d0c66070..c0e5e0d69 100644
--- a/src/core/justifier.cpp
+++ b/src/core/justifier.cpp
@@ -396,7 +396,7 @@ const Controller::ControllerInfo Justifier::INFO = {ControllerType::Justifier,
                                                     s_settings,
                                                     Controller::VibrationCapabilities::NoVibration};
 
-void Justifier::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void Justifier::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
 
diff --git a/src/core/justifier.h b/src/core/justifier.h
index b82eff6a1..27de367d8 100644
--- a/src/core/justifier.h
+++ b/src/core/justifier.h
@@ -40,7 +40,7 @@ public:
   void Reset() override;
   bool DoState(StateWrapper& sw, bool apply_input_state) override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
   float GetBindState(u32 index) const override;
   void SetBindState(u32 index, float value) override;
diff --git a/src/core/negcon.cpp b/src/core/negcon.cpp
index 59c8b5030..f4f89dcee 100644
--- a/src/core/negcon.cpp
+++ b/src/core/negcon.cpp
@@ -345,7 +345,7 @@ const Controller::ControllerInfo NeGcon::INFO = {
   ControllerType::NeGcon, "NeGcon",   TRANSLATE_NOOP("ControllerType", "NeGcon"),    ICON_PF_GAMEPAD,
   s_binding_info,         s_settings, Controller::VibrationCapabilities::NoVibration};
 
-void NeGcon::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void NeGcon::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
   m_steering_modifier = {
diff --git a/src/core/negcon.h b/src/core/negcon.h
index fa3bdeb75..a2393ce8d 100644
--- a/src/core/negcon.h
+++ b/src/core/negcon.h
@@ -100,7 +100,7 @@ public:
   u32 GetButtonStateBits() const override;
   std::optional<u32> GetAnalogInputBytes() const override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
 private:
   enum class TransferState : u8
diff --git a/src/core/negcon_rumble.cpp b/src/core/negcon_rumble.cpp
index 53020556a..01c732c7a 100644
--- a/src/core/negcon_rumble.cpp
+++ b/src/core/negcon_rumble.cpp
@@ -777,7 +777,7 @@ const Controller::ControllerInfo NeGconRumble::INFO = {ControllerType::NeGconRum
                                                        s_settings,
                                                        Controller::VibrationCapabilities::LargeSmallMotors};
 
-void NeGconRumble::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void NeGconRumble::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
   m_steering_deadzone = si.GetFloatValue(section, "SteeringDeadzone", 0.10f);
diff --git a/src/core/negcon_rumble.h b/src/core/negcon_rumble.h
index 43141fea9..59c1a5fc4 100644
--- a/src/core/negcon_rumble.h
+++ b/src/core/negcon_rumble.h
@@ -69,7 +69,7 @@ public:
   u32 GetButtonStateBits() const override;
   std::optional<u32> GetAnalogInputBytes() const override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
 private:
   using MotorState = std::array<u8, NUM_MOTORS>;
diff --git a/src/core/playstation_mouse.cpp b/src/core/playstation_mouse.cpp
index d6b1f3a87..d748fe3ee 100644
--- a/src/core/playstation_mouse.cpp
+++ b/src/core/playstation_mouse.cpp
@@ -182,7 +182,7 @@ bool PlayStationMouse::Transfer(const u8 data_in, u8* data_out)
   }
 }
 
-void PlayStationMouse::LoadSettings(SettingsInterface& si, const char* section, bool initial)
+void PlayStationMouse::LoadSettings(const SettingsInterface& si, const char* section, bool initial)
 {
   Controller::LoadSettings(si, section, initial);
 
diff --git a/src/core/playstation_mouse.h b/src/core/playstation_mouse.h
index 38c33cd95..3a412cef6 100644
--- a/src/core/playstation_mouse.h
+++ b/src/core/playstation_mouse.h
@@ -39,7 +39,7 @@ public:
   void ResetTransferState() override;
   bool Transfer(const u8 data_in, u8* data_out) override;
 
-  void LoadSettings(SettingsInterface& si, const char* section, bool initial) override;
+  void LoadSettings(const SettingsInterface& si, const char* section, bool initial) override;
 
 private:
   enum class TransferState : u8
diff --git a/src/core/settings.cpp b/src/core/settings.cpp
index afd58d2b7..d2d69a9d7 100644
--- a/src/core/settings.cpp
+++ b/src/core/settings.cpp
@@ -146,7 +146,7 @@ void Settings::UpdateOverclockActive()
   cpu_overclock_active = (cpu_overclock_enable && (cpu_overclock_numerator != 1 || cpu_overclock_denominator != 1));
 }
 
-void Settings::Load(SettingsInterface& si, SettingsInterface& controller_si)
+void Settings::Load(const SettingsInterface& si, const SettingsInterface& controller_si)
 {
   region =
     ParseConsoleRegionName(
diff --git a/src/core/settings.h b/src/core/settings.h
index d5a134778..f99113e74 100644
--- a/src/core/settings.h
+++ b/src/core/settings.h
@@ -368,7 +368,7 @@ struct Settings
     DEFAULT_GPU_MAX_RUN_AHEAD = 128,
   };
 
-  void Load(SettingsInterface& si, SettingsInterface& controller_si);
+  void Load(const SettingsInterface& si, const SettingsInterface& controller_si);
   void Save(SettingsInterface& si, bool ignore_base) const;
   static void Clear(SettingsInterface& si);
 
diff --git a/src/core/system.h b/src/core/system.h
index 29f6eff0f..598dd0167 100644
--- a/src/core/system.h
+++ b/src/core/system.h
@@ -473,7 +473,7 @@ void IdlePollUpdate();
 
 namespace Host {
 /// Called with the settings lock held, when system settings are being loaded (should load input sources, etc).
-void LoadSettings(SettingsInterface& si, std::unique_lock<std::mutex>& lock);
+void LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& lock);
 
 /// Called after settings are updated.
 void CheckForSettingsChanges(const Settings& old_settings);
diff --git a/src/duckstation-qt/qthost.cpp b/src/duckstation-qt/qthost.cpp
index d99242f9c..7a4783736 100644
--- a/src/duckstation-qt/qthost.cpp
+++ b/src/duckstation-qt/qthost.cpp
@@ -615,14 +615,8 @@ bool QtHost::SetDataDirectory()
   return true;
 }
 
-void Host::LoadSettings(SettingsInterface& si, std::unique_lock<std::mutex>& lock)
+void Host::LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& lock)
 {
-  g_emu_thread->loadSettings(si);
-}
-
-void EmuThread::loadSettings(SettingsInterface& si)
-{
-  //
 }
 
 void EmuThread::checkForSettingsChanges(const Settings& old_settings)
@@ -1972,7 +1966,7 @@ void Host::ReportDebuggerMessage(std::string_view message)
   emit g_emu_thread->debuggerMessageReported(QString::fromUtf8(message));
 }
 
-void Host::AddFixedInputBindings(SettingsInterface& si)
+void Host::AddFixedInputBindings(const SettingsInterface& si)
 {
 }
 
diff --git a/src/duckstation-qt/qthost.h b/src/duckstation-qt/qthost.h
index 6fa2d6609..8fccd971d 100644
--- a/src/duckstation-qt/qthost.h
+++ b/src/duckstation-qt/qthost.h
@@ -105,7 +105,6 @@ public:
   void wakeThread();
 
   bool shouldRenderToMain() const;
-  void loadSettings(SettingsInterface& si);
   void checkForSettingsChanges(const Settings& old_settings);
 
   void bootOrLoadState(std::string path);
diff --git a/src/duckstation-regtest/regtest_host.cpp b/src/duckstation-regtest/regtest_host.cpp
index 9464d0e75..ef2581233 100644
--- a/src/duckstation-regtest/regtest_host.cpp
+++ b/src/duckstation-regtest/regtest_host.cpp
@@ -204,7 +204,7 @@ SmallString Host::TranslatePluralToSmallString(const char* context, const char*
   return ret;
 }
 
-void Host::LoadSettings(SettingsInterface& si, std::unique_lock<std::mutex>& lock)
+void Host::LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& lock)
 {
 }
 
@@ -450,7 +450,7 @@ const char* InputManager::ConvertHostKeyboardCodeToIcon(u32 code)
   return nullptr;
 }
 
-void Host::AddFixedInputBindings(SettingsInterface& si)
+void Host::AddFixedInputBindings(const SettingsInterface& si)
 {
   // noop
 }
diff --git a/src/util/audio_stream.cpp b/src/util/audio_stream.cpp
index 3f8b83443..31ce20236 100644
--- a/src/util/audio_stream.cpp
+++ b/src/util/audio_stream.cpp
@@ -31,7 +31,7 @@ AudioStream::DeviceInfo::DeviceInfo(std::string name_, std::string display_name_
 
 AudioStream::DeviceInfo::~DeviceInfo() = default;
 
-void AudioStreamParameters::Load(SettingsInterface& si, const char* section)
+void AudioStreamParameters::Load(const SettingsInterface& si, const char* section)
 {
   stretch_mode =
     AudioStream::ParseStretchMode(
diff --git a/src/util/audio_stream.h b/src/util/audio_stream.h
index 127e9ec7c..45c2ba10e 100644
--- a/src/util/audio_stream.h
+++ b/src/util/audio_stream.h
@@ -71,7 +71,7 @@ struct AudioStreamParameters
   static constexpr bool DEFAULT_STRETCH_USE_QUICKSEEK = false;
   static constexpr bool DEFAULT_STRETCH_USE_AA_FILTER = false;
 
-  void Load(SettingsInterface& si, const char* section);
+  void Load(const SettingsInterface& si, const char* section);
   void Save(SettingsInterface& si, const char* section) const;
   void Clear(SettingsInterface& si, const char* section);
 
diff --git a/src/util/dinput_source.cpp b/src/util/dinput_source.cpp
index a8dbf3d11..97e89b51f 100644
--- a/src/util/dinput_source.cpp
+++ b/src/util/dinput_source.cpp
@@ -59,7 +59,7 @@ std::string DInputSource::GetDeviceIdentifier(u32 index)
 static constexpr std::array<const char*, DInputSource::NUM_HAT_DIRECTIONS> s_hat_directions = {
   {"Up", "Down", "Left", "Right"}};
 
-bool DInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+bool DInputSource::Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   m_dinput_module = LoadLibraryW(L"dinput8");
   if (!m_dinput_module)
@@ -103,7 +103,7 @@ bool DInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex
   return true;
 }
 
-void DInputSource::UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+void DInputSource::UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   // noop
 }
diff --git a/src/util/dinput_source.h b/src/util/dinput_source.h
index 10d3da355..f22dd8c73 100644
--- a/src/util/dinput_source.h
+++ b/src/util/dinput_source.h
@@ -33,8 +33,8 @@ public:
   DInputSource();
   ~DInputSource() override;
 
-  bool Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
-  void UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  bool Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  void UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
   bool ReloadDevices() override;
   void Shutdown() override;
 
diff --git a/src/util/input_manager.cpp b/src/util/input_manager.cpp
index 0fca23857..40383baa9 100644
--- a/src/util/input_manager.cpp
+++ b/src/util/input_manager.cpp
@@ -113,8 +113,8 @@ static void UpdatePointerCount();
 static bool IsAxisHandler(const InputEventHandler& handler);
 static float ApplySingleBindingScale(float sensitivity, float deadzone, float value);
 
-static void AddHotkeyBindings(SettingsInterface& si);
-static void AddPadBindings(SettingsInterface& si, const std::string& section, u32 pad,
+static void AddHotkeyBindings(const SettingsInterface& si);
+static void AddPadBindings(const SettingsInterface& si, const std::string& section, u32 pad,
                            const Controller::ControllerInfo* cinfo);
 static void UpdateContinuedVibration();
 static void GenerateRelativeMouseEvents();
@@ -123,12 +123,12 @@ static bool DoEventHook(InputBindingKey key, float value);
 static bool PreprocessEvent(InputBindingKey key, float value, GenericInputBinding generic_key);
 static bool ProcessEvent(InputBindingKey key, float value, bool skip_button_handlers);
 
-static void LoadMacroButtonConfig(SettingsInterface& si, const std::string& section, u32 pad,
+static void LoadMacroButtonConfig(const SettingsInterface& si, const std::string& section, u32 pad,
                                   const Controller::ControllerInfo* cinfo);
 static void ApplyMacroButton(u32 pad, const MacroButton& mb);
 static void UpdateMacroButtons();
 
-static void UpdateInputSourceState(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock,
+static void UpdateInputSourceState(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock,
                                    InputSourceType type, std::unique_ptr<InputSource> (*factory_function)());
 } // namespace InputManager
 
@@ -809,7 +809,7 @@ std::vector<const HotkeyInfo*> InputManager::GetHotkeyList()
   return ret;
 }
 
-void InputManager::AddHotkeyBindings(SettingsInterface& si)
+void InputManager::AddHotkeyBindings(const SettingsInterface& si)
 {
   for (const HotkeyInfo* hotkey_list : s_hotkey_list)
   {
@@ -824,7 +824,7 @@ void InputManager::AddHotkeyBindings(SettingsInterface& si)
   }
 }
 
-void InputManager::AddPadBindings(SettingsInterface& si, const std::string& section, u32 pad_index,
+void InputManager::AddPadBindings(const SettingsInterface& si, const std::string& section, u32 pad_index,
                                   const Controller::ControllerInfo* cinfo)
 {
   for (const Controller::ControllerBindingInfo& bi : cinfo->bindings)
@@ -1669,7 +1669,7 @@ void InputManager::UpdateContinuedVibration()
 // Macros
 // ------------------------------------------------------------------------
 
-void InputManager::LoadMacroButtonConfig(SettingsInterface& si, const std::string& section, u32 pad,
+void InputManager::LoadMacroButtonConfig(const SettingsInterface& si, const std::string& section, u32 pad,
                                          const Controller::ControllerInfo* cinfo)
 {
   s_macro_buttons[pad] = {};
@@ -1816,7 +1816,7 @@ bool InputManager::DoEventHook(InputBindingKey key, float value)
 // Binding Updater
 // ------------------------------------------------------------------------
 
-void InputManager::ReloadBindings(SettingsInterface& binding_si, SettingsInterface& hotkey_binding_si)
+void InputManager::ReloadBindings(const SettingsInterface& binding_si, const SettingsInterface& hotkey_binding_si)
 {
   PauseVibration();
 
@@ -2002,7 +2002,7 @@ GenericInputBindingMapping InputManager::GetGenericBindingMapping(std::string_vi
   return mapping;
 }
 
-bool InputManager::IsInputSourceEnabled(SettingsInterface& si, InputSourceType type)
+bool InputManager::IsInputSourceEnabled(const SettingsInterface& si, InputSourceType type)
 {
 #ifdef __ANDROID__
   // Force Android source to always be enabled so nobody accidentally breaks it via ini.
@@ -2013,7 +2013,7 @@ bool InputManager::IsInputSourceEnabled(SettingsInterface& si, InputSourceType t
   return si.GetBoolValue("InputSources", InputManager::InputSourceToString(type), GetInputSourceDefaultEnabled(type));
 }
 
-void InputManager::UpdateInputSourceState(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock,
+void InputManager::UpdateInputSourceState(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock,
                                           InputSourceType type, std::unique_ptr<InputSource> (*factory_function)())
 {
   const bool enabled = IsInputSourceEnabled(si, type);
@@ -2045,7 +2045,7 @@ void InputManager::UpdateInputSourceState(SettingsInterface& si, std::unique_loc
   }
 }
 
-void InputManager::ReloadSources(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+void InputManager::ReloadSources(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
 #ifdef _WIN32
   UpdateInputSourceState(si, settings_lock, InputSourceType::DInput, &InputSource::CreateDInputSource);
diff --git a/src/util/input_manager.h b/src/util/input_manager.h
index 70185a698..dc835bb0f 100644
--- a/src/util/input_manager.h
+++ b/src/util/input_manager.h
@@ -251,13 +251,13 @@ std::vector<InputBindingKey> EnumerateMotors();
 GenericInputBindingMapping GetGenericBindingMapping(std::string_view device);
 
 /// Returns true if the specified input source is enabled.
-bool IsInputSourceEnabled(SettingsInterface& si, InputSourceType type);
+bool IsInputSourceEnabled(const SettingsInterface& si, InputSourceType type);
 
 /// Re-parses the config and registers all hotkey and pad bindings.
-void ReloadBindings(SettingsInterface& si, SettingsInterface& hotkey_binding_si);
+void ReloadBindings(const SettingsInterface& si, const SettingsInterface& hotkey_binding_si);
 
 /// Re-parses the sources part of the config and initializes any backends.
-void ReloadSources(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock);
+void ReloadSources(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock);
 
 /// Called when a device change is triggered by the system (DBT_DEVNODES_CHANGED on Windows).
 /// Returns true if any device changes are detected.
@@ -364,7 +364,7 @@ void OnInputDeviceDisconnected(InputBindingKey key, std::string_view identifier)
 
 namespace Host {
 /// Adds any fixed bindings from the host.
-void AddFixedInputBindings(SettingsInterface& si);
+void AddFixedInputBindings(const SettingsInterface& si);
 
 /// Called when a new input device is connected.
 void OnInputDeviceConnected(std::string_view identifier, std::string_view device_name);
diff --git a/src/util/input_source.h b/src/util/input_source.h
index 9d185028b..29fcf3689 100644
--- a/src/util/input_source.h
+++ b/src/util/input_source.h
@@ -22,8 +22,8 @@ public:
   InputSource();
   virtual ~InputSource();
 
-  virtual bool Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) = 0;
-  virtual void UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) = 0;
+  virtual bool Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) = 0;
+  virtual void UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) = 0;
   virtual bool ReloadDevices() = 0;
   virtual void Shutdown() = 0;
 
diff --git a/src/util/sdl_input_source.cpp b/src/util/sdl_input_source.cpp
index 269e815e1..bba9f0bf1 100644
--- a/src/util/sdl_input_source.cpp
+++ b/src/util/sdl_input_source.cpp
@@ -161,7 +161,7 @@ SDLInputSource::~SDLInputSource()
   Assert(m_controllers.empty());
 }
 
-bool SDLInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+bool SDLInputSource::Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   LoadSettings(si);
   settings_lock.unlock();
@@ -171,7 +171,7 @@ bool SDLInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mut
   return result;
 }
 
-void SDLInputSource::UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+void SDLInputSource::UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   const bool old_controller_enhanced_mode = m_controller_enhanced_mode;
   const bool old_controller_ps5_player_led = m_controller_ps5_player_led;
@@ -213,7 +213,7 @@ void SDLInputSource::Shutdown()
   ShutdownSubsystem();
 }
 
-void SDLInputSource::LoadSettings(SettingsInterface& si)
+void SDLInputSource::LoadSettings(const SettingsInterface& si)
 {
   for (u32 i = 0; i < MAX_LED_COLORS; i++)
   {
@@ -240,7 +240,7 @@ void SDLInputSource::LoadSettings(SettingsInterface& si)
 #endif
 }
 
-u32 SDLInputSource::GetRGBForPlayerId(SettingsInterface& si, u32 player_id)
+u32 SDLInputSource::GetRGBForPlayerId(const SettingsInterface& si, u32 player_id)
 {
   return ParseRGBForPlayerId(
     si.GetStringValue("SDLExtra", fmt::format("Player{}LED", player_id).c_str(), s_sdl_default_led_colors[player_id]),
diff --git a/src/util/sdl_input_source.h b/src/util/sdl_input_source.h
index 34682f793..6f0940b90 100644
--- a/src/util/sdl_input_source.h
+++ b/src/util/sdl_input_source.h
@@ -21,8 +21,8 @@ public:
   SDLInputSource();
   ~SDLInputSource();
 
-  bool Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
-  void UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  bool Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  void UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
   bool ReloadDevices() override;
   void Shutdown() override;
 
@@ -42,7 +42,7 @@ public:
 
   SDL_Joystick* GetJoystickForDevice(std::string_view device);
 
-  static u32 GetRGBForPlayerId(SettingsInterface& si, u32 player_id);
+  static u32 GetRGBForPlayerId(const SettingsInterface& si, u32 player_id);
   static u32 ParseRGBForPlayerId(std::string_view str, u32 player_id);
 
   static bool IsHandledInputEvent(const SDL_Event* ev);
@@ -73,7 +73,7 @@ private:
 
   bool InitializeSubsystem();
   void ShutdownSubsystem();
-  void LoadSettings(SettingsInterface& si);
+  void LoadSettings(const SettingsInterface& si);
   void SetHints();
 
   ControllerDataVector::iterator GetControllerDataForJoystickId(int id);
diff --git a/src/util/win32_raw_input_source.cpp b/src/util/win32_raw_input_source.cpp
index 116b0b364..20338e871 100644
--- a/src/util/win32_raw_input_source.cpp
+++ b/src/util/win32_raw_input_source.cpp
@@ -29,7 +29,7 @@ Win32RawInputSource::Win32RawInputSource() = default;
 
 Win32RawInputSource::~Win32RawInputSource() = default;
 
-bool Win32RawInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+bool Win32RawInputSource::Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   if (!RegisterDummyClass())
   {
@@ -52,7 +52,7 @@ bool Win32RawInputSource::Initialize(SettingsInterface& si, std::unique_lock<std
   return true;
 }
 
-void Win32RawInputSource::UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+void Win32RawInputSource::UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
 }
 
diff --git a/src/util/win32_raw_input_source.h b/src/util/win32_raw_input_source.h
index de8fc5436..bac1574f1 100644
--- a/src/util/win32_raw_input_source.h
+++ b/src/util/win32_raw_input_source.h
@@ -17,8 +17,8 @@ public:
   Win32RawInputSource();
   ~Win32RawInputSource();
 
-  bool Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
-  void UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  bool Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  void UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
   bool ReloadDevices() override;
   void Shutdown() override;
 
diff --git a/src/util/xinput_source.cpp b/src/util/xinput_source.cpp
index 6627af0e1..3e95d1692 100644
--- a/src/util/xinput_source.cpp
+++ b/src/util/xinput_source.cpp
@@ -113,7 +113,7 @@ XInputSource::XInputSource() = default;
 
 XInputSource::~XInputSource() = default;
 
-bool XInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+bool XInputSource::Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
   // xinput1_3.dll is flawed and obsolete, but it's also commonly used by wrappers.
   // For this reason, try to load it *only* from the application directory, and not system32.
@@ -155,7 +155,7 @@ bool XInputSource::Initialize(SettingsInterface& si, std::unique_lock<std::mutex
   return true;
 }
 
-void XInputSource::UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
+void XInputSource::UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock)
 {
 }
 
diff --git a/src/util/xinput_source.h b/src/util/xinput_source.h
index cc9d9310a..dd087d56e 100644
--- a/src/util/xinput_source.h
+++ b/src/util/xinput_source.h
@@ -35,8 +35,8 @@ public:
   XInputSource();
   ~XInputSource();
 
-  bool Initialize(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
-  void UpdateSettings(SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  bool Initialize(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
+  void UpdateSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& settings_lock) override;
   bool ReloadDevices() override;
   void Shutdown() override;