I have a old great Technics Amp Id like to keep its a SU 610. I have just purchased a Harmon Kardon 20/HKTS 30 home theatre system 5.1 surround. Id like to connect this to my Technics Amp and LG 42 Ld450 TV..is this possible? I have No centre for middle speaker. I was told id need a Decoder or HMDI and cables? Which would these be please i'm not so technical.Thanks for your suggestions.