diff --git a/thirdparty/rexglue-sdk/src/native/audio/audio_system.cpp b/thirdparty/rexglue-sdk/src/native/audio/audio_system.cpp
index 10c5f301..5b0127ae 100644
--- a/thirdparty/rexglue-sdk/src/native/audio/audio_system.cpp
+++ b/thirdparty/rexglue-sdk/src/native/audio/audio_system.cpp
@@ -19,6 +19,16 @@ REXCVAR_DEFINE_BOOL(audio_trace_render_driver_verbose, false, "Audio",
                     "Trace render-driver activity");
 REXCVAR_DEFINE_BOOL(audio_deep_trace, false, "Audio",
                     "Enable verbose runtime audio tracing");
+REXCVAR_DEFINE_BOOL(audio_xma_loop_guard, true, "Audio",
+                    "Require a real loop window (loop_start < loop_end, "
+                    "read_offset >= loop_end) before engaging XMA loop "
+                    "handling, as in current Xenia master (PR #1808, debugged "
+                    "on Ace Combat 6). Off: legacy behavior, where streamed "
+                    "voices carrying degenerate loop metadata (loop_count="
+                    "0xff, loop_start == loop_end == 0) re-fire the loop "
+                    "machinery on every input buffer swap, truncating/"
+                    "skipping subframes of the stream (confirmed firing on "
+                    "AC6 cutscene streams via the deep-trace counter).");
 REXCVAR_DEFINE_BOOL(audio_xma_preserve_timeline, true, "Audio",
                     "When the XMA decoder backend rejects a damaged frame, emit that "
                     "frame's worth of silence instead of dropping it. The input read "
diff --git a/thirdparty/rexglue-sdk/src/native/audio/xma/context.cpp b/thirdparty/rexglue-sdk/src/native/audio/xma/context.cpp
index 6550bc44..cb39582a 100644
--- a/thirdparty/rexglue-sdk/src/native/audio/xma/context.cpp
+++ b/thirdparty/rexglue-sdk/src/native/audio/xma/context.cpp
@@ -1,4 +1,4 @@
-/**
+/**
  * ReXGlue native audio runtime
  * Part of the AC6 Recompilation project
  */
@@ -17,6 +17,7 @@
 #include <native/stream.h>
 
 REXCVAR_DECLARE(bool, audio_deep_trace);
+REXCVAR_DECLARE(bool, audio_xma_loop_guard);
 REXCVAR_DECLARE(bool, audio_xma_preserve_timeline);
 
 namespace rex::audio {
@@ -342,7 +343,31 @@ void XmaContext::UpdateLoopStatus(XMA_CONTEXT_DATA* data) {
   const uint32_t loop_start = std::max(kBitsPerPacketHeader, data->loop_start);
   const uint32_t loop_end = std::max(kBitsPerPacketHeader, data->loop_end);
 
-  if (data->input_buffer_read_offset != loop_end) {
+  if (REXCVAR_GET(audio_xma_loop_guard)) {
+    // Xenia master's TrySetupNextLoop guard (PR #1808, debugged on Ace
+    // Combat 6): streamed voices can carry degenerate loop metadata
+    // (loop_count=0xff, loop_start == loop_end == 0). The clamps above turn
+    // that into start == end == kBitsPerPacketHeader, and SwapInputBuffer
+    // resets the read offset to exactly kBitsPerPacketHeader, so without a
+    // real-window check every buffer swap re-fires the loop machinery -
+    // the frame output limit truncates that frame and the loop-start skip
+    // drops subframes. Require loop_start < loop_end (raw values) and use
+    // master's read_offset >= loop_end trigger.
+    if (data->loop_start >= data->loop_end ||
+        data->input_buffer_read_offset < loop_end) {
+      if (data->loop_start >= data->loop_end &&
+          data->input_buffer_read_offset == loop_end && IsDeepTraceEnabled()) {
+        REXAPU_DEBUG(
+            "XmaContext {}: loop guard suppressed degenerate loop fire "
+            "(loop_start={} loop_end={} loop_count={} read_offset={})",
+            id(), static_cast<uint32_t>(data->loop_start),
+            static_cast<uint32_t>(data->loop_end),
+            static_cast<uint32_t>(data->loop_count),
+            static_cast<uint32_t>(data->input_buffer_read_offset));
+      }
+      return;
+    }
+  } else if (data->input_buffer_read_offset != loop_end) {
     return;
   }