diff --git a/Marlin/Configuration_adv.h b/Marlin/Configuration_adv.h
index fd598e59e..95e93eb28 100644
--- a/Marlin/Configuration_adv.h
+++ b/Marlin/Configuration_adv.h
@@ -3306,13 +3306,18 @@
  */
 //#define POWER_MONITOR_CURRENT   // Monitor the system current
 //#define POWER_MONITOR_VOLTAGE   // Monitor the system voltage
-#if EITHER(POWER_MONITOR_CURRENT, POWER_MONITOR_VOLTAGE)
-  #define POWER_MONITOR_VOLTS_PER_AMP   0.05000   // Input voltage to the MCU analog pin per amp  - DO NOT apply more than ADC_VREF!
-  #define POWER_MONITOR_CURRENT_OFFSET -1         // Offset value for current sensors with linear function output
-  #define POWER_MONITOR_VOLTS_PER_VOLT  0.11786   // Input voltage to the MCU analog pin per volt - DO NOT apply more than ADC_VREF!
+
+#if ENABLED(POWER_MONITOR_CURRENT)
+  #define POWER_MONITOR_VOLTS_PER_AMP    0.05000  // Input voltage to the MCU analog pin per amp  - DO NOT apply more than ADC_VREF!
+  #define POWER_MONITOR_CURRENT_OFFSET   0        // Offset (in amps) applied to the calculated current
   #define POWER_MONITOR_FIXED_VOLTAGE   13.6      // Voltage for a current sensor with no voltage sensor (for power display)
 #endif
 
+#if ENABLED(POWER_MONITOR_VOLTAGE)
+  #define POWER_MONITOR_VOLTS_PER_VOLT  0.077933  // Input voltage to the MCU analog pin per volt - DO NOT apply more than ADC_VREF!
+  #define POWER_MONITOR_VOLTAGE_OFFSET  0         // Offset (in volts) applied to the calculated voltage
+#endif
+
 /**
  * CNC Coordinate Systems
  *
diff --git a/Marlin/src/feature/power_monitor.cpp b/Marlin/src/feature/power_monitor.cpp
index 97c4a9336..1937a5410 100644
--- a/Marlin/src/feature/power_monitor.cpp
+++ b/Marlin/src/feature/power_monitor.cpp
@@ -26,8 +26,11 @@
 
 #include "power_monitor.h"
 
-#include "../lcd/marlinui.h"
-#include "../lcd/lcdprint.h"
+#if HAS_LCD_MENU
+  #include "../lcd/marlinui.h"
+  #include "../lcd/lcdprint.h"
+#endif
+
 #include "../libs/numtostr.h"
 
 uint8_t PowerMonitor::flags; // = 0
@@ -54,7 +57,7 @@ PowerMonitor power_monitor; // Single instance - this calls the constructor
     }
   #endif
 
-  #if HAS_POWER_MONITOR_VREF
+  #if ENABLED(POWER_MONITOR_VOLTAGE)
     void PowerMonitor::draw_voltage() {
       const float volts = getVolts();
       lcd_put_u8str(volts < 100 ? ftostr31ns(volts) : ui16tostr4rj((uint16_t)volts));
diff --git a/Marlin/src/feature/power_monitor.h b/Marlin/src/feature/power_monitor.h
index f378ee2a1..f6e0b292e 100644
--- a/Marlin/src/feature/power_monitor.h
+++ b/Marlin/src/feature/power_monitor.h
@@ -23,7 +23,7 @@
 
 #include "../inc/MarlinConfig.h"
 
-#define PM_SAMPLE_RANGE 1024
+#define PM_SAMPLE_RANGE HAL_ADC_RANGE
 #define PM_K_VALUE      6
 #define PM_K_SCALE      6
 
@@ -35,7 +35,7 @@ struct pm_lpf_t {
     filter_buf = filter_buf - (filter_buf >> K_VALUE) + (uint32_t(sample) << K_SCALE);
   }
   void capture() {
-    value = filter_buf * (SCALE * (1.0f / (1UL << (PM_K_VALUE + PM_K_SCALE)))) + (POWER_MONITOR_CURRENT_OFFSET);
+    value = filter_buf * (SCALE * (1.0f / (1UL << (PM_K_VALUE + PM_K_SCALE))));
   }
   void reset(uint16_t reset_value = 0) {
     filter_buf = uint32_t(reset_value) << (K_VALUE + K_SCALE);
@@ -69,19 +69,15 @@ public:
   };
 
   #if ENABLED(POWER_MONITOR_CURRENT)
-    FORCE_INLINE static float getAmps() { return amps.value; }
+    FORCE_INLINE static float getAmps() { return amps.value + (POWER_MONITOR_CURRENT_OFFSET); }
     void add_current_sample(const uint16_t value) { amps.add_sample(value); }
   #endif
 
-  #if HAS_POWER_MONITOR_VREF
-    #if ENABLED(POWER_MONITOR_VOLTAGE)
-      FORCE_INLINE static float getVolts() { return volts.value; }
-    #else
-      FORCE_INLINE static float getVolts() { return POWER_MONITOR_FIXED_VOLTAGE; }  // using a specified fixed valtage as the voltage measurement
-    #endif
-    #if ENABLED(POWER_MONITOR_VOLTAGE)
-      void add_voltage_sample(const uint16_t value) { volts.add_sample(value); }
-    #endif
+  #if ENABLED(POWER_MONITOR_VOLTAGE)
+    FORCE_INLINE static float getVolts() { return volts.value + (POWER_MONITOR_VOLTAGE_OFFSET); }
+    void add_voltage_sample(const uint16_t value) { volts.add_sample(value); }
+  #else
+    FORCE_INLINE static float getVolts() { return POWER_MONITOR_FIXED_VOLTAGE; }
   #endif
 
   #if HAS_POWER_MONITOR_WATTS
@@ -98,7 +94,7 @@ public:
       FORCE_INLINE static void set_current_display(const bool b) { SET_BIT_TO(flags, PM_DISP_BIT_I, b); }
       FORCE_INLINE static void toggle_current_display() { TBI(flags, PM_DISP_BIT_I); }
     #endif
-    #if HAS_POWER_MONITOR_VREF
+    #if ENABLED(POWER_MONITOR_VOLTAGE)
       static void draw_voltage();
       FORCE_INLINE static bool voltage_display_enabled() { return TEST(flags, PM_DISP_BIT_V); }
       FORCE_INLINE static void set_voltage_display(const bool b) { SET_BIT_TO(flags, PM_DISP_BIT_V, b); }
diff --git a/Marlin/src/gcode/feature/power_monitor/M430.cpp b/Marlin/src/gcode/feature/power_monitor/M430.cpp
index 955940445..34430fbc3 100644
--- a/Marlin/src/gcode/feature/power_monitor/M430.cpp
+++ b/Marlin/src/gcode/feature/power_monitor/M430.cpp
@@ -42,7 +42,7 @@ void GcodeSuite::M430() {
     #if ENABLED(POWER_MONITOR_CURRENT)
       if (parser.seen('I')) { power_monitor.set_current_display(parser.value_bool()); do_report = false; }
     #endif
-    #if HAS_POWER_MONITOR_VREF
+    #if ENABLED(POWER_MONITOR_VOLTAGE)
       if (parser.seen('V')) { power_monitor.set_voltage_display(parser.value_bool()); do_report = false; }
     #endif
     #if HAS_POWER_MONITOR_WATTS
@@ -53,11 +53,11 @@ void GcodeSuite::M430() {
     SERIAL_ECHOLNPAIR(
       #if ENABLED(POWER_MONITOR_CURRENT)
         "Current: ", power_monitor.getAmps(), "A"
-        #if HAS_POWER_MONITOR_VREF
+        #if ENABLED(POWER_MONITOR_VOLTAGE)
           "  "
         #endif
       #endif
-      #if HAS_POWER_MONITOR_VREF
+      #if ENABLED(POWER_MONITOR_VOLTAGE)
         "Voltage: ", power_monitor.getVolts(), "V"
       #endif
       #if HAS_POWER_MONITOR_WATTS
diff --git a/Marlin/src/inc/Conditionals_adv.h b/Marlin/src/inc/Conditionals_adv.h
index 2177dc486..3bd77d754 100644
--- a/Marlin/src/inc/Conditionals_adv.h
+++ b/Marlin/src/inc/Conditionals_adv.h
@@ -498,12 +498,9 @@
 // Power Monitor sensors
 #if EITHER(POWER_MONITOR_CURRENT, POWER_MONITOR_VOLTAGE)
   #define HAS_POWER_MONITOR 1
-#endif
-#if ENABLED(POWER_MONITOR_CURRENT) && defined(POWER_MONITOR_FIXED_VOLTAGE)
-  #define HAS_POWER_MONITOR_VREF 1
-#endif
-#if BOTH(HAS_POWER_MONITOR_VREF, POWER_MONITOR_CURRENT)
-  #define HAS_POWER_MONITOR_WATTS 1
+  #if ENABLED(POWER_MONITOR_CURRENT) && (ENABLED(POWER_MONITOR_VOLTAGE) || defined(POWER_MONITOR_FIXED_VOLTAGE))
+    #define HAS_POWER_MONITOR_WATTS 1
+  #endif
 #endif
 
 // Flag if an EEPROM type is pre-selected
diff --git a/Marlin/src/lcd/dogm/status_screen_DOGM.cpp b/Marlin/src/lcd/dogm/status_screen_DOGM.cpp
index 7e638a645..119de19d9 100644
--- a/Marlin/src/lcd/dogm/status_screen_DOGM.cpp
+++ b/Marlin/src/lcd/dogm/status_screen_DOGM.cpp
@@ -136,7 +136,7 @@
     #if ENABLED(POWER_MONITOR_CURRENT)
       const bool iflag = power_monitor.current_display_enabled();
     #endif
-    #if HAS_POWER_MONITOR_VREF
+    #if ENABLED(POWER_MONITOR_VOLTAGE)
       const bool vflag = power_monitor.voltage_display_enabled();
     #endif
 
@@ -148,7 +148,7 @@
       }
     #elif ENABLED(POWER_MONITOR_CURRENT)
       power_monitor.display_item = 0;
-    #elif HAS_POWER_MONITOR_VREF
+    #elif ENABLED(POWER_MONITOR_VOLTAGE)
       power_monitor.display_item = 1;
     #endif
 
@@ -157,7 +157,7 @@
       #if ENABLED(POWER_MONITOR_CURRENT)
         if (power_monitor.display_item == 0 && !iflag) ++power_monitor.display_item;
       #endif
-      #if HAS_POWER_MONITOR_VREF
+      #if ENABLED(POWER_MONITOR_VOLTAGE)
         if (power_monitor.display_item == 1 && !vflag) ++power_monitor.display_item;
       #endif
       #if HAS_POWER_MONITOR_WATTS
@@ -170,7 +170,7 @@
       #if ENABLED(POWER_MONITOR_CURRENT)                // Current
         case 0: if (iflag) power_monitor.draw_current(); break;
       #endif
-      #if HAS_POWER_MONITOR_VREF                        // Voltage
+      #if ENABLED(POWER_MONITOR_VOLTAGE)                        // Voltage
         case 1: if (vflag) power_monitor.draw_voltage(); break;
       #endif
       #if HAS_POWER_MONITOR_WATTS                       // Power
diff --git a/Marlin/src/lcd/menu/menu_power_monitor.cpp b/Marlin/src/lcd/menu/menu_power_monitor.cpp
index d31ebd36b..b43327f63 100644
--- a/Marlin/src/lcd/menu/menu_power_monitor.cpp
+++ b/Marlin/src/lcd/menu/menu_power_monitor.cpp
@@ -42,7 +42,7 @@ void menu_power_monitor() {
   }
   #endif
 
-  #if HAS_POWER_MONITOR_VREF
+  #if ENABLED(POWER_MONITOR_VOLTAGE)
   {
     bool ena = power_monitor.voltage_display_enabled();
     EDIT_ITEM(bool, MSG_VOLTAGE, &ena, power_monitor.toggle_voltage_display);
diff --git a/Marlin/src/pins/lpc1768/pins_GMARSH_X6_REV1.h b/Marlin/src/pins/lpc1768/pins_GMARSH_X6_REV1.h
index 0df8b1029..cbf6ca2d3 100644
--- a/Marlin/src/pins/lpc1768/pins_GMARSH_X6_REV1.h
+++ b/Marlin/src/pins/lpc1768/pins_GMARSH_X6_REV1.h
@@ -119,6 +119,7 @@
 // Misc. Functions
 //
 #define LED_PIN                            P1_31
+#define POWER_MONITOR_VOLTAGE_PIN       P0_25_A2
 
 //
 // LCD
@@ -156,9 +157,8 @@
   #define SD_MISO_PIN                      P0_17
   #define SD_MOSI_PIN                      P0_18
   #define SD_SS_PIN                        P0_16
+  #define SD_DETECT_PIN                    P1_22
 #elif SD_CONNECTION_IS(ONBOARD)
-  #undef SD_DETECT_PIN
-  #define SD_DETECT_PIN                    P0_27
   #define SD_SCK_PIN                       P0_07
   #define SD_MISO_PIN                      P0_08
   #define SD_MOSI_PIN                      P0_09