/****************************
 *   LeftRightPlayback.h
 ***************************/

// This class creates an instance of PAPlayback
#include "PAPlayback.h"

class LeftRightPlayback
{
     public:
          typedef enum
          {
               LEFT,
               RIGHT,
               LEFTRIGHT,
               MIXED
          } channel;
};



/****************************
 *      PAPlayback.h
 ***************************/

// We include this for a typedef used in other classes also
#include "LeftRightPlayback.h"

// I tried with and without the forward declaration:
class LeftRightPlayback;

class PAPlayback
{
     public:
          void setType( LeftRightPlayback::channel );
};