I just purchased the Sony mhc ec99i shelf system. It has only one input jack (for PC or other digital source). I would like to be able to use our turntable, which is an older, analog model, for the purpose of playing our vinyl through the system. Can I just purchase an RCA stereo jack adaptor? Or am I doomed? Thanks so much for your help! And here is a link to the owner's manual for the mhc ec99i: http://www.docs.sony.com/release/MHCEC99I_EN.pdf
You need a phono preamp to amplify and equalise the output of your turntable to match the line-level input on the Sony. If in US try Radio Shack, in UK Maplin or Richer Sounds. Ebay also a probable source.
You also need a cable to link the mini-jack on the sony to the RCA/phono sockets likely to be on the phono preamp. Luckily, you already probably have the standard lead that links computer audio output (mini jack) to other devices (phono sockets) -- like speakers.
Shouldn't be any technical issues but make sure the turntable audio earth lead is secured to the preamp to avoid hum.