diff --git a/client/src/contexts/DeviceContext.tsx b/client/src/contexts/DeviceContext.tsx
index c46675c..619cd8d 100644
--- a/client/src/contexts/DeviceContext.tsx
+++ b/client/src/contexts/DeviceContext.tsx
@@ -1,6 +1,7 @@
 import React, { createContext, useCallback, useContext, useEffect, useRef, useState } from "react";
 import {
   DeviceState,
+  getHomeVolumeMax,
   LuxsinAPI,
   MOCK_DEVICE_STATE,
   MOCK_PEQ_STATE,
@@ -213,12 +214,16 @@ export function DeviceProvider({ children }: { children: React.ReactNode }) {
   }, [api, isDemoMode, applyPeqFiltersToState]);
 
   // Optimistic setters
+  const maxVolume = getHomeVolumeMax(deviceState);
   const setVolume = useCallback((v: number) => {
-    setDeviceState(prev => prev ? { ...prev, volume: v } : prev);
+    if (!Number.isFinite(v)) return;
+    // 指令和乐观状态使用同一上限，防止任何首页入口发送超限音量。
+    const volume = Math.max(0, Math.min(maxVolume, Math.round(v)));
+    setDeviceState(prev => prev ? { ...prev, volume } : prev);
     if (!isDemoMode && api) {
-      api.setVolume(v).catch(console.error);
+      api.setVolume(volume).catch(console.error);
     }
-  }, [api, isDemoMode]);
+  }, [api, isDemoMode, maxVolume]);
 
   const setInput = useCallback((v: number) => {
     setDeviceState(prev => prev ? { ...prev, input: v } : prev);
diff --git a/client/src/lib/luxsinApi.ts b/client/src/lib/luxsinApi.ts
index 63d0b5d..4fcd1a0 100644
--- a/client/src/lib/luxsinApi.ts
+++ b/client/src/lib/luxsinApi.ts
@@ -21,6 +21,32 @@ export function volumeToDb(vol: number): number {
   return (vol - 200) / 2;
 }
 
+/** 耳机输出（协议索引 2）使用设置上限；其他输出及未返回设置的旧固件保持 0dB。 */
+export function getHomeVolumeMax(
+  state: Pick<DeviceState, "output" | "hpMaxVolume"> | null | undefined,
+): number {
+  if (state?.output !== 2) return 200;
+  const rawIndex = Number(state.hpMaxVolume ?? 0);
+  const index = Number.isFinite(rawIndex)
+    ? Math.max(0, Math.min(10, Math.trunc(rawIndex)))
+    : 0;
+  // 每档降低 5dB，即 10 个设备音量单位。
+  return dbToVolume(-5 * index);
+}
+
+/**
+ * 耳机输出（协议索引 2）且用户设置了耳机最大音量（低于 0dB）时，返回该上限的 dB 值（负数）；
+ * 其他输出、未设置（0 档）或旧固件（无 hpMaxVolume）返回 null。
+ */
+export function getHeadphoneMaxVolumeDb(
+  state: Pick<DeviceState, "output" | "hpMaxVolume"> | null | undefined,
+): number | null {
+  if (state?.output !== 2) return null;
+  const rawIndex = Number(state.hpMaxVolume ?? 0);
+  if (!Number.isFinite(rawIndex) || Math.trunc(rawIndex) <= 0) return null;
+  return volumeToDb(getHomeVolumeMax(state));
+}
+
 export function decodeCustomBase64(encoded: string): string {
   let translated = "";
   for (let i = 0; i < encoded.length; i++) {
diff --git a/client/src/locales/data-en.json b/client/src/locales/data-en.json
index cf2affe..0f5145f 100644
--- a/client/src/locales/data-en.json
+++ b/client/src/locales/data-en.json
@@ -26,6 +26,7 @@
     "volumeMaxConfirmOk": "Set to maximum",
     "volumePassthroughLockedToast": "Volume is in passthrough mode and cannot be adjusted.",
     "volumePassthroughLockedHint": "Volume is in passthrough mode and cannot be adjusted.",
+    "hpMaxVolumeHint": "Headphone max volume is set. Maximum: {db}dB",
     "powerOffToastDemo": "Demo mode: shutdown command sent.",
     "powerOffToastSent": "Shutdown command sent.",
     "doubleClickHint": "Double-click to enter",
diff --git a/client/src/locales/data-zh-HK.json b/client/src/locales/data-zh-HK.json
index be47a5a..05e3e50 100644
--- a/client/src/locales/data-zh-HK.json
+++ b/client/src/locales/data-zh-HK.json
@@ -26,6 +26,7 @@
     "volumeMaxConfirmOk": "設為最大",
     "volumePassthroughLockedToast": "目前為音量直通模式，無法調節音量",
     "volumePassthroughLockedHint": "目前為音量直通模式，無法調節音量",
+    "hpMaxVolumeHint": "已設定耳機最大音量，最大音量為：{db}dB",
     "powerOffToastDemo": "演示模式：已傳送關機指令",
     "powerOffToastSent": "已傳送關機指令",
     "doubleClickHint": "按兩下進入",
diff --git a/client/src/locales/data-zh.json b/client/src/locales/data-zh.json
index 6f6f591..ec2d100 100644
--- a/client/src/locales/data-zh.json
+++ b/client/src/locales/data-zh.json
@@ -26,6 +26,7 @@
     "volumeMaxConfirmOk": "设为最大",
     "volumePassthroughLockedToast": "当前为音量直通模式，无法调节音量",
     "volumePassthroughLockedHint": "当前为音量直通模式，无法调节音量",
+    "hpMaxVolumeHint": "已设置耳机最大音量，最大音量为：{db}dB",
     "powerOffToastDemo": "演示模式：已发送关机指令",
     "powerOffToastSent": "已发送关机指令",
     "doubleClickHint": "双击进入",
diff --git a/client/src/pages/Home.tsx b/client/src/pages/Home.tsx
index b1ec5cf..3b9e10b 100644
--- a/client/src/pages/Home.tsx
+++ b/client/src/pages/Home.tsx
@@ -23,7 +23,7 @@ import {
   AlertDialogHeader,
   AlertDialogTitle,
 } from "@/components/ui/alert-dialog";
-import { INPUT_LABELS, OUTPUT_LABELS } from "@/lib/luxsinApi";
+import { getHeadphoneMaxVolumeDb, getHomeVolumeMax, INPUT_LABELS, OUTPUT_LABELS } from "@/lib/luxsinApi";
 import { cn } from "@/lib/utils";
 import {
   ChevronRight,
@@ -250,7 +250,10 @@ export default function Home() {
     return null;
   }, [volumeConfirm, homeText]);
 
-  const [localVol, setLocalVol] = useState(deviceState?.volume ?? 100);
+  const maxVolume = getHomeVolumeMax(deviceState);
+  const [volumeDraft, setLocalVol] = useState(deviceState?.volume ?? 100);
+  // 上限或输出切换时立即约束显示，拖动中也不能保留超限值。
+  const localVol = Math.max(0, Math.min(maxVolume, volumeDraft));
   const isDragging = useRef(false);
   const knobDraggingRef = useRef(false);
   const knobActivePointerIdRef = useRef<number | null>(null);
@@ -259,10 +262,10 @@ export default function Home() {
   const knobLastVolRef = useRef<number>(localVol);
 
   useEffect(() => {
-    if (!isDragging.current && deviceState?.volume !== undefined) {
-      setLocalVol(deviceState.volume);
-    }
-  }, [deviceState?.volume]);
+    setLocalVol(current => Math.max(0, Math.min(maxVolume,
+      !isDragging.current && deviceState?.volume !== undefined ? deviceState.volume : current,
+    )));
+  }, [deviceState?.volume, maxVolume]);
 
   useEffect(() => {
     knobLastVolRef.current = localVol;
@@ -444,16 +447,25 @@ export default function Home() {
   const vuLabel = `${homeText.vu ?? "VU表"}${(ds.vu ?? 0) + 1}`;
   const bypassOn = (ds.dsp_enable ?? 0) === 0;
 
+  // 耳机输出且已设置耳机最大音量时，提示当前上限，避免用户误以为还能加到 0dB。
+  const hpMaxVolumeDb = getHeadphoneMaxVolumeDb(ds);
+  const hpMaxVolumeHint =
+    hpMaxVolumeDb === null
+      ? null
+      : (homeText.hpMaxVolumeHint ?? "已设置耳机最大音量，最大音量为：{db}dB").replace(
+          "{db}",
+          String(hpMaxVolumeDb),
+        );
+
   // Home 的 volume 取值为 0..200，对应 dB = (v - 200) / 2
   // 因此 1 个 volume 单位 = 0.5dB
   // AudioPage 的 soundStep：0->0.5dB, 1->1dB, 2->2dB, 3->3dB
   // 换算为 volume 单位：0.5/1/2/3 dB -> 1/2/4/6
   const fineVolumeStep = [1, 2, 4, 6][ds.soundStep ?? 1] ?? 1;
 
-  // Slider fill % (0-200 → 0-100%)
-  const fillPct = (localVol / 200) * 100;
-  // Knob angle (map 0..200 -> -135..+135 degrees)
-  const knobAngle = -135 + (localVol / 200) * 270;
+  // 滑条填充和旋钮角度均按当前输出的最大音量映射。
+  const fillPct = (localVol / maxVolume) * 100;
+  const knobAngle = -135 + (localVol / maxVolume) * 270;
 
   const pointAngle = (clientX: number, clientY: number, rect: DOMRect) => {
     const cx = rect.left + rect.width / 2;
@@ -488,9 +500,9 @@ export default function Home() {
     const rect = el.getBoundingClientRect();
     const a = pointAngle(e.clientX, e.clientY, rect);
     const delta = normalizeDelta(a - knobStartAngleRef.current);
-    // 270deg travel -> full scale; 1 rad maps to ~200/(1.5*pi) volume steps
-    const stepsPerRad = 200 / (Math.PI * 1.5);
-    const next = Math.max(0, Math.min(200, Math.round(knobStartVolRef.current + delta * stepsPerRad)));
+    // 270 度行程对应当前允许的完整音量范围。
+    const stepsPerRad = maxVolume / (Math.PI * 1.5);
+    const next = Math.max(0, Math.min(maxVolume, Math.round(knobStartVolRef.current + delta * stepsPerRad)));
     setLocalVol(next);
     knobLastVolRef.current = next;
   };
@@ -677,7 +689,7 @@ export default function Home() {
             />
             <ThumbOnlyRangeSlider
               min={0}
-              max={200}
+              max={maxVolume}
               value={localVol}
               disabled={volumeControlsLocked}
               onChange={(v) => {
@@ -728,7 +740,7 @@ export default function Home() {
             }}
             onClick={() => {
               guardVolumeChange(() => {
-                const next = Math.max(0, Math.min(200, localVol - fineVolumeStep));
+                const next = Math.max(0, Math.min(maxVolume, localVol - fineVolumeStep));
                 setLocalVol(next);
                 setVolume(next);
               });
@@ -744,7 +756,7 @@ export default function Home() {
           <button
             type="button"
             aria-label="Increase volume"
-            disabled={volumeControlsLocked || localVol >= 200}
+            disabled={volumeControlsLocked || localVol >= maxVolume}
             className="w-10 h-10 rounded-full flex items-center justify-center transition-all active:scale-95 disabled:opacity-30 disabled:cursor-not-allowed"
             style={{
               background: "rgba(44,44,46,0.6)",
@@ -753,7 +765,7 @@ export default function Home() {
             }}
             onClick={() => {
               guardVolumeChange(() => {
-                const next = Math.max(0, Math.min(200, localVol + fineVolumeStep));
+                const next = Math.max(0, Math.min(maxVolume, localVol + fineVolumeStep));
                 setLocalVol(next);
                 setVolume(next);
               });
@@ -763,6 +775,16 @@ export default function Home() {
           </button>
         </div>
 
+        {hpMaxVolumeHint && (
+          <p
+            className="mt-2 text-center text-[12px] leading-relaxed"
+            style={{ color: "rgba(255,255,255,0.5)" }}
+            role="status"
+          >
+            {hpMaxVolumeHint}
+          </p>
+        )}
+
         {/* Bluetooth info */}
         {ds.bt_status !== 0 && (
           <div className="mt-3 px-3 py-3 text-center">
@@ -937,8 +959,8 @@ export default function Home() {
                   setLocalVol(0);
                   setVolume(0);
                 } else if (volumeConfirm === "max") {
-                  setLocalVol(200);
-                  setVolume(200);
+                  setLocalVol(maxVolume);
+                  setVolume(maxVolume);
                 }
                 setVolumeConfirm(null);
               }}