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/application/apps/ui_mictx.cpp

@@ -51,11 +51,11 @@ void MicTXView::on_tx_progress(const bool done) {
 }
 
 void MicTXView::configure_baseband() {
-	baseband::set_audiotx_data(
+	baseband::set_audiotx_config(
 		sampling_rate / 20,		// Update vu-meter at 20Hz
 		transmitting ? transmitter_model.channel_bandwidth() : 0,
 		mic_gain,
-		TONES_F2D(tone_key_frequency(tone_key_index)),
+		TONES_F2D(tone_key_frequency(tone_key_index), sampling_rate),
 		0.2		// 20% mix
 	);
 }