Audio preview is failing to set the width of the player as defined in the Options Mediaplayer tab
In /helpers/jdownloads.php line 819 or there abouts is the statment
$player_maxwidth = 'max-width:'.(int)$params->get('html5player_audio.width').'px; ';
It should be an underscore rather than a point
$player_maxwidth = 'max-width:'.(int)$params->get('html5player_audio_width').'px; ';
Colin