uses
 MMSystem;

 procedure SetVolume(const volL, volR: Word);
 var
 hWO: HWAVEOUT;
 waveF: TWAVEFORMATEX;
 vol: DWORD;
 begin
 // init TWAVEFORMATEX 
 FillChar(waveF, SizeOf(waveF), 0);
 // open WaveMapper = std output of playsound 
 waveOutOpen(@hWO, WAVE_MAPPER, @waveF, 0, 0, 0);
 vol := volL + volR shl 16;
 // set volume 
 waveOutSetVolume(hWO, vol);
 waveOutClose(hWO);
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 begin
 SetVolume(14000, 14000);
 end;