It looks like you can buy the speaker cords with the connectors on them. The price looks a little ridiculous... http://servicesales.sel.sony.com/ecom/accessories/web/productSearch.do?searchOperation=modelSearch&modelNum=DAVHDX500&searchText=DAVHDX500&category=4&categoryName=Home%20Audio
You could try calling Sony's parts department. When you have a part number, they'll be more able to help you. If a price is obviously ridiculous, you may be able to talk the price down some. Be nice... Way too much money because a plug fell off and it's nothing standard you can replace... Bad design, bad quality plug failed, unfair expense... Please, is there anything at all you can do to help me?