Nice jack socket,
I have an adapter which came from a seller in the States which only cost £2.00 including postage to the UK and it works perfectly with no sound loss.
When I saw this adapter for the price it seemed to me logical to not bother hunting for a stand alone plug, because of the time and effort to track one down.
Oh how I wish Tandys which was Radio Shack here, was still tradeing in the UK, as it was a very handy store to pop in and get one off components
In fact we had a lot of small electronic spare parts stores a one time.
Nice diagram Alex