I have a Sony MDX-6500 mini disk head. I want to connect a CD changer. According to the Sony site (which masn't been updated since it came out)the correct changer is the CDX-737. The guy in my local Audio shop reckons that the standard hasn't changed for years and wants to sell me a T69. I want to believe him 'cos there are loads on ebay. How do I find out?