Finally found what was eating all the RAM :D

Re-enabled the tone key selector in Soundboard
Soundboard now uses OutputStream, like Replay
Constexpr'd a bunch of consts which were going to BSS section
Exiting an app now goes back to main menu
Cleaned up Message array

firmware/baseband/proc_audiotx.hpp

@@ -23,10 +23,10 @@
 #ifndef __PROC_AUDIOTX_H__
 #define __PROC_AUDIOTX_H__
 
-#include "fifo.hpp"
 #include "baseband_processor.hpp"
 #include "baseband_thread.hpp"
 #include "tone_gen.hpp"
+#include "stream_output.hpp"
 
 class AudioTXProcessor : public BasebandProcessor {
 public:
@@ -35,27 +35,29 @@ public:
 	void on_message(const Message* const msg) override;
 
 private:
-	static constexpr size_t baseband_fs = 1536000U;
-	
-	bool configured = false;
+	size_t baseband_fs = 0;
 	
 	BasebandThread baseband_thread { baseband_fs, this, NORMALPRIO + 20, baseband::Direction::Transmit };
 	
-	int8_t audio_fifo_data[2048] { };
-	FIFO<int8_t> audio_fifo = { audio_fifo_data, 11 };	// 43ms @ 48000Hz
+	std::array<uint8_t, 64> audio { };
+	const buffer_t<uint8_t> audio_buffer {
+		audio.data(),
+		audio.size(),
+		baseband_fs / 8
+	};
+	
+	std::unique_ptr<StreamOutput> stream { };
 	
 	ToneGen tone_gen { };
 	
 	uint32_t fm_delta { 0 };
-	uint32_t divider { };
-	uint32_t as { 0 };
 	uint32_t phase { 0 }, sphase { 0 };
 	int8_t out_sample { };
-	int32_t sample { 0 }, delta { };
-	
+	int32_t sample { 0 }, audio_sample { 0 }, delta { };
 	int8_t re { 0 }, im { 0 };
 	
-	bool asked { false };
+	size_t spectrum_interval_samples = 0;
+	size_t spectrum_samples = 0;
 
 	//int16_t audio_data[64];
 	/*const buffer_s16_t preview_audio_buffer {
@@ -63,6 +65,14 @@ private:
 		sizeof(int16_t)*64
 	};*/
 	
+	bool configured { false };
+	uint32_t bytes_read { 0 };
+	
+	void samplerate_config(const SamplerateConfigMessage& message);
+	void audio_config(const AudioTXConfigMessage& message);
+	void replay_config(const ReplayConfigMessage& message);
+	
+	TXProgressMessage txprogress_message { };
 	RequestSignalMessage sig_message { RequestSignalMessage::Signal::FillRequest };
 };