diff -ruN a/src/framework/audio/driver/platform/lin/pwaudiodriver.cpp b/src/framework/audio/driver/platform/lin/pwaudiodriver.cpp
--- a/src/framework/audio/driver/platform/lin/pwaudiodriver.cpp	2026-11-05 22:48:21.745460035 +0000
+++ b/src/framework/audio/driver/platform/lin/pwaudiodriver.cpp	2026-11-05 22:48:21.763460036 +0000
@@ -511,7 +511,13 @@
     }
 
     const auto maxFrames = buf->datas[0].maxsize / m_stride;
+#if PW_CHECK_VERSION(0, 3, 49)
     const auto numFrames = b->requested ? SPA_MIN(b->requested, maxFrames) : maxFrames;
+#else
+    // pw_buffer::requested only exists since PipeWire 0.3.49 (Slackware 15.0 ships 0.3.44):
+    // fall back to the period we asked for via node.latency, bounded by the buffer size.
+    const auto numFrames = SPA_MIN(static_cast<decltype(maxFrames)>(m_spec.output.samplesPerChannel), maxFrames);
+#endif
     const auto len = numFrames * m_stride;
 
     m_spec.callback(dst, len);
diff -ruN a/src/framework/audio/main/internal/audioconfiguration.cpp b/src/framework/audio/main/internal/audioconfiguration.cpp
--- a/src/framework/audio/main/internal/audioconfiguration.cpp	2026-11-05 22:49:03.124461992 +0000
+++ b/src/framework/audio/main/internal/audioconfiguration.cpp	2026-11-05 22:49:03.142461993 +0000
@@ -23,6 +23,9 @@
 
 //TODO: remove with global clearing of Q_OS_*** defines
 #include <QtGlobal>
+#include <QFileInfo>
+
+#include "muse_framework_config.h"
 
 #include "global/settings.h"
 
@@ -62,7 +65,21 @@
 #if defined(Q_OS_WIN)
     settings()->setDefaultValue(AUDIO_API_KEY, Val("WASAPI"));
 #elif defined(Q_OS_LINUX) || defined(Q_OS_FREEBSD)
-    settings()->setDefaultValue(AUDIO_API_KEY, Val("ALSA"));
+    {
+        // The ALSA driver hangs the GUI thread when ALSA "default" is routed through
+        // pipewire-alsa (close() joins an audio thread stuck in snd_pcm_writei/drain).
+        // Prefer the native PipeWire driver when it is built in and a server is running.
+        std::string defaultApi = "ALSA";
+#ifdef MUSE_MODULE_AUDIO_PIPEWIRE
+        const QString runtimeDir = qEnvironmentVariable("PIPEWIRE_RUNTIME_DIR", qEnvironmentVariable("XDG_RUNTIME_DIR"));
+        const QString remote = qEnvironmentVariable("PIPEWIRE_REMOTE", QStringLiteral("pipewire-0"));
+        if (!qEnvironmentVariableIsSet("MUSESCORE_FORCE_ALSA") && !runtimeDir.isEmpty()
+            && QFileInfo::exists(runtimeDir + QLatin1Char('/') + remote)) {
+            defaultApi = "PipeWire";
+        }
+#endif
+        settings()->setDefaultValue(AUDIO_API_KEY, Val(defaultApi));
+    }
 #elif defined(Q_OS_MACOS)
     settings()->setDefaultValue(AUDIO_API_KEY, Val("CoreAudio"));
 #endif