diff --git a/Components/AudioToggle/AudioToggle.hpp b/Components/AudioToggle/AudioToggle.hpp
index e3d29ac30..f00f1304d 100644
--- a/Components/AudioToggle/AudioToggle.hpp
+++ b/Components/AudioToggle/AudioToggle.hpp
@@ -29,9 +29,12 @@ class Toggle: public Outputs::Speaker::SampleSource {
 		bool get_output();
 
 	private:
+		// Accessed on the calling thread.
 		bool is_enabled_ = false;
-		int16_t level_ = 0, volume_ = 0;
 		Concurrency::DeferringAsyncTaskQueue &audio_queue_;
+
+		// Accessed on the audio thread.
+		int16_t level_ = 0, volume_ = 0;
 };
 
 }
diff --git a/Machines/AppleII/AppleII.cpp b/Machines/AppleII/AppleII.cpp
index 7095a4aa9..fda5dd81c 100644
--- a/Machines/AppleII/AppleII.cpp
+++ b/Machines/AppleII/AppleII.cpp
@@ -51,8 +51,9 @@ class ConcreteMachine:
 		void update_video() {
 			video_->run_for(cycles_since_video_update_.flush());
 		}
+		static const int audio_divider = 8;
 		void update_audio() {
-			speaker_.run_for(cycles_since_audio_update_.divide(Cycles(16)));
+			speaker_.run_for(audio_queue_, cycles_since_audio_update_.divide(Cycles(audio_divider)));
 		}
 
 		uint8_t ram_[48*1024];
@@ -82,7 +83,7 @@ class ConcreteMachine:
 
 			// The speaker, however, should think it is clocked at half the master clock, per a general
 			// decision to sample it at seven times the CPU clock (plus stretches).
-			speaker_.set_input_rate(static_cast<float>(master_clock / (2.0 * 16.0)));
+			speaker_.set_input_rate(static_cast<float>(master_clock / (2.0 * static_cast<float>(audio_divider))));
 
 			// Also, start with randomised memory contents.
 			Memory::Fuzz(ram_, sizeof(ram_));
diff --git a/Outputs/Speaker/Implementation/LowpassSpeaker.hpp b/Outputs/Speaker/Implementation/LowpassSpeaker.hpp
index e22a30a72..19655f980 100644
--- a/Outputs/Speaker/Implementation/LowpassSpeaker.hpp
+++ b/Outputs/Speaker/Implementation/LowpassSpeaker.hpp
@@ -86,6 +86,18 @@ template <typename T> class LowpassSpeaker: public Speaker {
 			filter_parameters_.parameters_are_dirty = true;
 		}
 
+		/*!
+			Schedules an advancement by the number of cycles specified on the provided queue.
+			The speaker will advance by obtaining data from the sample source supplied
+			at construction, filtering it and passing it on to the speaker's delegate if there is one.
+		*/
+		void run_for(Concurrency::DeferringAsyncTaskQueue &queue, const Cycles cycles) {
+			queue.defer([this, cycles] {
+				run_for(cycles);
+			});
+		}
+
+	private:
 		/*!
 			Advances by the number of cycles specified, obtaining data from the sample source supplied
 			at construction, filtering it and passing it on to the speaker's delegate if there is one.
@@ -173,16 +185,6 @@ template <typename T> class LowpassSpeaker: public Speaker {
 			// TODO: input rate is less than output rate
 		}
 
-		/*!
-			Provides a convenience shortcut for deferring a call to run_for.
-		*/
-		void run_for(Concurrency::DeferringAsyncTaskQueue &queue, const Cycles cycles) {
-			queue.defer([this, cycles] {
-				run_for(cycles);
-			});
-		}
-
-	private:
 		T &sample_source_;
 
 		std::size_t output_buffer_pointer_ = 0;