Add a note regarding plughw

Author: abique

src/host/alsa/enumerate.rs

@@ -58,7 +58,14 @@ impl Iterator for Devices {
                 continue;
             };
 
-            let pcm_id = format!("plughw:{}", card.get_index());
+            // Using plughw adds the ALSA plug layer, which can do sample type conversion,
+            // sample rate convertion, ...
+            // It is convenient, but at the same time not suitable for pro-audio as it hides
+            // the actual device capabilities and perform audio manipulation under your feet,
+            // for example sample rate conversion, sample format conversion, adds dummy channels,
+            // ...
+            const USE_PLUGHW : bool = false;
+            let pcm_id = if USE_PLUGHW { format!("plughw:{}", card.get_index()) } else { ctl_id };
             if let Ok(handles) = DeviceHandles::open(&pcm_id) {
                 return Some(Device {
                     name: card_name.to_string(),