diff --git a/src/xenia/apu/audio_system.cc b/src/xenia/apu/audio_system.cc
index 8f2c24f14..22e719c35 100644
--- a/src/xenia/apu/audio_system.cc
+++ b/src/xenia/apu/audio_system.cc
@@ -103,8 +103,6 @@ X_STATUS AudioSystem::Setup() {
   }
   registers_.next_context = 1;
 
-  // Threads
-
   worker_running_ = true;
   worker_thread_ =
       kernel::object_ref<kernel::XHostThread>(new kernel::XHostThread(
@@ -366,10 +364,29 @@ void AudioSystem::ReleaseXmaContext(uint32_t guest_ptr) {
       context.decoder->DiscardPacket();
 
       context.lock.unlock();
+      break;
     }
   }
 }
 
+bool AudioSystem::BlockOnXmaContext(uint32_t guest_ptr, bool poll) {
+  std::lock_guard<xe::mutex> lock(lock_);
+  for (uint32_t n = 0; n < kXmaContextCount; n++) {
+    XMAContext& context = xma_context_array_[n];
+    if (context.guest_ptr == guest_ptr) {
+      if (!context.lock.try_lock()) {
+        if (poll) {
+          return false;
+        }
+        context.lock.lock();
+      }
+      context.lock.unlock();
+      return true;
+    }
+  }
+  return true;
+}
+
 X_STATUS AudioSystem::RegisterClient(uint32_t callback, uint32_t callback_arg,
                                      size_t* out_index) {
   assert_true(unused_clients_.size());
@@ -450,6 +467,8 @@ uint64_t AudioSystem::ReadRegister(uint32_t addr) {
 }
 
 void AudioSystem::WriteRegister(uint32_t addr, uint64_t value) {
+  SCOPE_profile_cpu_f("apu");
+
   uint32_t r = addr & 0xFFFF;
   value = xe::byte_swap(uint32_t(value));
   XELOGAPU("WriteRegister(%.4X, %.8X)", r, value);
@@ -486,12 +505,12 @@ void AudioSystem::WriteRegister(uint32_t addr, uint64_t value) {
 
         data.Store(context_ptr);
         context.lock.unlock();
-
-        // Signal the decoder thread
-        decoder_fence_.Signal();
       }
       value >>= 1;
     }
+
+    // Signal the decoder thread to start processing.
+    decoder_fence_.Signal();
   } else if (r >= 0x1A40 && r <= 0x1A40 + 9 * 4) {
     // Context lock command.
     // This requests a lock by flagging the context.
diff --git a/src/xenia/apu/audio_system.h b/src/xenia/apu/audio_system.h
index 80c084410..53b3a0ec0 100644
--- a/src/xenia/apu/audio_system.h
+++ b/src/xenia/apu/audio_system.h
@@ -126,6 +126,7 @@ class AudioSystem {
   }
   uint32_t AllocateXmaContext();
   void ReleaseXmaContext(uint32_t guest_ptr);
+  bool BlockOnXmaContext(uint32_t guest_ptr, bool poll);
 
   X_STATUS RegisterClient(uint32_t callback, uint32_t callback_arg,
                           size_t* out_index);
diff --git a/src/xenia/cpu/mmio_handler_win.cc b/src/xenia/cpu/mmio_handler_win.cc
index 86beca9ec..184cf1163 100644
--- a/src/xenia/cpu/mmio_handler_win.cc
+++ b/src/xenia/cpu/mmio_handler_win.cc
@@ -11,6 +11,8 @@
 
 #include <Windows.h>
 
+#include "xenia/profiling.h"
+
 namespace xe {
 void CrashDump();
 }  // namespace xe
@@ -61,6 +63,8 @@ WinMMIOHandler::~WinMMIOHandler() {
 // addresses in our range and call into the registered handlers, if any.
 // If there are none, we continue.
 LONG CALLBACK MMIOExceptionHandler(PEXCEPTION_POINTERS ex_info) {
+  SCOPE_profile_cpu_i("cpu", "MMIOExceptionHandler");
+
   // http://msdn.microsoft.com/en-us/library/ms679331(v=vs.85).aspx
   // http://msdn.microsoft.com/en-us/library/aa363082(v=vs.85).aspx
   auto code = ex_info->ExceptionRecord->ExceptionCode;
diff --git a/src/xenia/kernel/xboxkrnl_audio_xma.cc b/src/xenia/kernel/xboxkrnl_audio_xma.cc
index a2c51b79c..4ec2c182a 100644
--- a/src/xenia/kernel/xboxkrnl_audio_xma.cc
+++ b/src/xenia/kernel/xboxkrnl_audio_xma.cc
@@ -87,8 +87,7 @@ void StoreXmaContextIndexedRegister(KernelState* state, uint32_t base_reg,
                       XMAContextData::kSize;
   uint32_t reg_num = base_reg + (hw_index >> 5) * 4;
   uint32_t reg_value = 1 << (hw_index & 0x1F);
-  xe::store<uint32_t>(state->memory()->TranslateVirtual(0x7FEA0000 + reg_num),
-                      reg_value);
+  audio_system->WriteRegister(reg_num, xe::byte_swap(reg_value));
 }
 
 SHIM_CALL XMAInitializeContext_shim(PPCContext* ppc_state, KernelState* state) {
@@ -372,7 +371,9 @@ SHIM_CALL XMADisableContext_shim(PPCContext* ppc_state, KernelState* state) {
 
   X_HRESULT result = X_E_SUCCESS;
   StoreXmaContextIndexedRegister(state, 0x1A40, context_ptr);
-  XMAContextData context(SHIM_MEM_ADDR(context_ptr));
+  if (!state->emulator()->audio_system()->BlockOnXmaContext(context_ptr, !wait)) {
+    result = X_E_FALSE;
+  }
 
   SHIM_SET_RETURN_32(result);
 }