Ok i have a first result:

Code:
for i:=0 to BufferSize div 2 do
  begin
    if ( l= true ) then
    begin
      PByteArray(dataR)^[iR]:=PByteArray(data)^[i*2];
      PByteArray(dataR)^[iR+1]:=PByteArray(data)^[i*2+1];
      ic:=ic+2;
      iR:=iR+2;
      l:=false;
    end
    else
    begin
      PByteArray(dataL)^[iL]:=PByteArray(data)^[i*2];
      PByteArray(dataL)^[iL+1]:=PByteArray(data)^[i*2+1];
      ic:=ic+2;
      iL:=iL+2;
      l:=true;
    end;
  end;

  alBufferData(Buffer, Format, dataR, BufferSize div 2, FRate);
So to get this further to work i need to have 2 sources with double buffering. Also note the div 2 for the buffersize. And yes the code needs much cleaning up.

I now need an .ogg or .mp3 file with heareable stereo effect to properly test it. My current test files are not suiteable. Does anyone here have such a thing lying around? I have not.