[FunkeXMix]

That was one issue, thanks for pointing it out. Second was a proper NCX markup which I fixed and kindlegen generated an enhanced PRC file without errors. File size is correct. But Kindle iPad app still claims that "There was a problem downloading the audio content of this title. Please remove the book from your device and re-download it."

I guess the app just has this limit built in if you sideload ebooks into it.

Working NCX code:

<navMap>
		
		<navPoint id="navPoint-1" playOrder="1">
      <navLabel>
        <text>Preface</text>
      </navLabel>
      <content src="first.xhtml#_idParaDest-2" />
    </navPoint>
	
	
	<navList>
     
       
		
        <navTarget id="audio_1">
		<navLabel>
        <text>audio_1</text>
      </navLabel>
            <content src="first.xhtml#audio_1"/>
			<audio src="audiovideo/myzuka.mp3"/>
        </navTarget>
    
    </navList>
	
	</navMap>