On My Nokkia 221T(Freeview Box)it has a coaxial digital out i bought a coaxial-optical convertor from maplin so i could conect it digtally to my hifi but the sound sounds limp compared to the analouge

Perhaps there's something dodgy about the converter. Mines connected without a converter and I've had no problems with the sound. The digital feed is at least as good as the analogue. I don't think you are likely to hear much quality difference due to the amout of compression the sounds gone through. It's certainly not CD quality sound. Infact it's not even NICAM quality sound in my opinion.