Is it really worth paying a lot for an optical digital cable? For example, will this £4 cable (http://www.tvcables.co.uk/cgi-bin/tvcables/TS002.html?id=noyZNmNy) be any worse than this £30 cable (http://www.tvcables.co.uk/cgi-bin/tvcables/XHD308-200.html?id=noyZNmNy).