uses MMSystem;

procedure TForm1.Button1Click(Sender: TObject);
var
 vol: longint;
 LVol, RVol: integer;
begin
 AuxGetVolume(ListBox1.ItemIndex, @Vol);
 LVol := Vol shr 16;
 if LVol < MaxWord - 1000 then
 LVol := LVol + 1000
 else
 LVol := MaxWord;
 RVol := (Vol shl 16) shr 16;
 if RVol < MaxWord - 1000 then
 RVol := RVol + 1000
 else
 RVol := MaxWord;
 AuxSetVolume(ListBox1.ItemIndex, LVol shl 16 + RVol);
end;

procedure TForm1.FormCreate(Sender: TObject);
var
 i: integer;
 cap: TAuxCaps;
begin
 for i := 0 to auxGetNumDevs - 1 do
 begin
 auxGetDevCaps(i, Addr(cap), SizeOf(cap));
 ListBox1.Items.Add(cap.szPname)
 end;
end;