don't wipe inapplicable sound config immediately

src/mixxx.cpp

@@ -61,6 +61,7 @@
 #include "skin/legacy/legacyskinparser.h"
 #include "skin/skinloader.h"
 #include "soundio/soundmanager.h"
+#include "soundio/soundmanagerconfig.h"
 #include "sources/soundsourceproxy.h"
 #include "track/track.h"
 #include "util/db/dbconnectionpooled.h"
@@ -640,7 +641,9 @@ void MixxxMainWindow::initialize(QApplication* pApp, const CmdlineArgs& args) {
     // https://bugs.launchpad.net/mixxx/+bug/1758189
     m_pPlayerManager->loadSamplers();
 
-    // Try open player device If that fails, the preference panel is opened.
+    // Sound hardware setup
+    // Try to open configured devices. If that fails, display dialogs
+    // that allow to either retry, reconfigure devices or exit.
     bool retryClicked;
     do {
         retryClicked = false;
@@ -658,11 +661,10 @@ void MixxxMainWindow::initialize(QApplication* pApp, const CmdlineArgs& args) {
         }
     } while (retryClicked);
 
-    // test for at least one out device, if none, display another dlg that
-    // says "mixxx will barely work with no outs"
-    // In case persisting errors, the user has already received a message
-    // box from the preferences dialog above. So we can watch here just the
-    // output count.
+    // Test for at least one output device. If none, display another dialog
+    // that says "mixxx will barely work with no outs".
+    // In case of persisting errors, the user has already received a message
+    // above. So we can just check the output count here.
     while (m_pSoundManager->getConfig().getOutputs().count() == 0) {
         // Exit when we press the Exit button in the noSoundDlg dialog
         // only call it if result != OK
@@ -673,7 +675,10 @@ void MixxxMainWindow::initialize(QApplication* pApp, const CmdlineArgs& args) {
         if (continueClicked) {
             break;
         }
-   }
+    }
+    // The user has either reconfigured devices or accepted no outputs,
+    // so it's now safe to write the new config to disk.
+    m_pSoundManager->getConfig().writeToDisk();
 
     // Load tracks in args.qlMusicFiles (command line arguments) into player
     // 1 and 2:
@@ -1035,6 +1040,7 @@ QDialog::DialogCode MixxxMainWindow::soundDeviceErrorDlg(
             m_pSoundManager->clearAndQueryDevices();
             // This way of opening the dialog allows us to use it synchronously
             m_pPrefDlg->setWindowModality(Qt::ApplicationModal);
+            // Open preferences, sound hardware page is selected (default on first call)
             m_pPrefDlg->exec();
             if (m_pPrefDlg->result() == QDialog::Accepted) {
                 return QDialog::Accepted;

src/mixxx.h

@@ -34,6 +34,7 @@ class SettingsManager;
 class BroadcastManager;
 class SkinLoader;
 class SoundManager;
+class SoundManagerConfig;
 class VinylControlManager;
 class WMainMenuBar;
 

src/soundio/soundmanager.cpp

@@ -81,7 +81,10 @@ SoundManager::SoundManager(UserSettingsPointer pConfig,
         m_config.loadDefaults(this, SoundManagerConfig::ALL);
     }
     checkConfig();
-    m_config.writeToDisk(); // in case anything changed by applying defaults
+    // Don't write config to disk, yet -- it may be reset to defaults in case
+    // previously configured devices were not found.
+    // Write new config after MixxxMainWindow::noOutputDlg where the user has
+    // a chance to keep the previous sound config (exit).
 }
 
 SoundManager::~SoundManager() {