Kung walang ground wire yung TT, most probably integrated na sa left RCA cord yung grounding nya. Meaning, you don't have a problem with ground anymore. Plug mo na lang sa amp mo, then play. Pag may humming, either naputol yung ground wire nya kaya wala kang makitang wire, or try to move the RCA plugs. Pag nawala, good. If not, pa-solder ka ng ground wire.