diff --git a/qml/Main.qml b/qml/Main.qml
index 6f2ea19..8e47fb9 100644
--- a/qml/Main.qml
+++ b/qml/Main.qml
@@ -44,11 +44,15 @@ ApplicationWindow {
             const savedOutputs = JSON.parse(appSettings.savedOutputDevices)
             for (let output of savedOutputs) {
                 createOutputDevice(output.name, output.host, output.port, output.type)
-                // Restore active state after creation
+                // Restore active state and source index offset after creation
+                const lastIdx = outputDevices.length - 1
+                if (output.sourceIndexOffset) {
+                    outputDevices[lastIdx].sourceIndexOffset = output.sourceIndexOffset
+                }
                 if (output.active === false) {
-                    outputDevices[outputDevices.length - 1].active = false
-                    updateOutputList()
+                    outputDevices[lastIdx].active = false
                 }
+                updateOutputList()
             }
         } catch (e) {
             console.log("Could not restore saved outputs:", e)
@@ -57,7 +61,7 @@ ApplicationWindow {
 
     function saveOutputDevices() {
         const toSave = outputDevices.map(function(d) {
-            return { name: d.name, host: d.host, port: d.port, type: d.type, active: d.active }
+            return { name: d.name, host: d.host, port: d.port, type: d.type, active: d.active, sourceIndexOffset: d.sourceIndexOffset || 0 }
         })
         appSettings.savedOutputDevices = JSON.stringify(toSave)
     }
@@ -109,7 +113,7 @@ ApplicationWindow {
         // Route to all active outputs
         for (let output of outputDevices) {
             if (output.active) {
-                const mapped = mapControlGRISMessage(command, sourceIndex, value, output.type)
+                const mapped = mapControlGRISMessage(command, sourceIndex + (output.sourceIndexOffset || 0), value, output.type)
                 if (mapped && mapped.length > 0) {
                     // Send each mapped message to output device
                     for (let msg of mapped) {
@@ -428,7 +432,8 @@ ApplicationWindow {
             host: host,
             port: port,
             type: type,
-            active: true
+            active: true,
+            sourceIndexOffset: 0
         })
 
         updateOutputList()
@@ -769,7 +774,34 @@ ApplicationWindow {
                                     elide: Text.ElideRight
                                     font.pixelSize: Math.min(11, window.height * 0.018)
                                 }
-                                
+
+                                Label {
+                                    text: "Offset:"
+                                    color: "#aaaaaa"
+                                    font.pixelSize: Math.min(11, window.height * 0.018)
+                                }
+
+                                TextField {
+                                    Layout.preferredWidth: 50
+                                    Layout.preferredHeight: 25
+                                    text: model.sourceIndexOffset !== undefined ? model.sourceIndexOffset : "0"
+                                    color: acceptableInput ? "#ffffff" : "#f00"
+                                    font.pixelSize: Math.min(11, window.height * 0.018)
+                                    horizontalAlignment: Text.AlignHCenter
+                                    validator: IntValidator { bottom: 0; top: 9999; }
+
+                                    background: Rectangle {
+                                        color: "#2a2a2a"
+                                        border.color: parent.focus ? "#5a5a5a" : "#4a4a4a"
+                                        radius: 2
+                                    }
+
+                                    onTextEdited: {
+                                        outputDevices[index].sourceIndexOffset = parseInt(text) || 0
+                                        saveOutputDevices()
+                                    }
+                                }
+
                                 Button {
                                     Layout.preferredWidth: Math.max(60, Math.min(80, window.width * 0.08))
                                     Layout.preferredHeight: 25