После многих проблем изоляции я получил этот фрагмент:

object Snippet  {
    def main(args: Array[String]): Unit = {
        println("Snip demo:: "+ util.Properties.versionString)
        println(" jvm "+System.getProperty("java.version"))
        import javax.sound.sampled._
        val mixers : Array[Mixer.Info] = javax.sound.sampled.AudioSystem.getMixerInfo()
        println(" Numer of mixers: "+ mixers.size)
        for (mi : Mixer.Info <- mixers ) { 
            println("mixer info "+mi.getName) 
        } 
    }
}

Удивительно, выход после запускаsbt run отличается от бегаscala:

$ sbt run
Loading /cygdrive/c/Program Files (x86)/sbt/bin/sbt-launch-lib.bash
[warn] The global sbt directory is now versioned and is located at         ....
[warn]   You are seeing this warning because there is global configuration ....
[warn]   The global sbt directory may be changed via the sbt.global.base system property.
[info] Set current project to snippet (in build file:/Documents/SbtProjects/Snippet/)
[info] Compiling 1 Scala source to Documents\SbtProjects\Snippet\target\scala-2.10\classes...
[info] Running Snippet
Snip demo:: version 2.10.2
 jvm 1.7.0_21
 Numer of mixers: 0
[success] Total time: 3 s, completed 10-Jun-2014 15:35:34

$ scala src/main/scala/snippet.scala
Snip demo:: version 2.10.2
 jvm 1.7.0_21
 Numer of mixers: 12
 mixer info Primary Sound Driver
 mixer info Speakers (Plantronics C320)
 mixer info Realtek Digital Output (Realtek High Definition Audio)
 mixer info Speakers (Realtek High Definition Audio)
 mixer info Realtek Digital Output(Optical) (Realtek High Definition Audio)
 mixer info Primary Sound Capture Driver
 mixer info Microphone (Plantronics C320)
 mixer info Port Speakers (Plantronics C320)
 mixer info Port Realtek Digital Output (Realtek
 mixer info Port Speakers (Realtek High Definiti
 mixer info Port Realtek Digital Output(Optical)
 mixer info Port Microphone (Plantronics C320)

Я должен упустить что-то очень фундаментальное. Любая помощь очень ценится.