I recently purchased the Logitech z906 surround sound system, and while I am very happy with the playback of Dolby Digital and DTS 5.1 tracks, Logitech's own 5.1 upconversion of stereo sources is very poor compared to Dolby Pro Logic encoding. I'm basically looking for a box to take the stereo (PCM and Dolby Digital 2.0) output via my TV's optical cable and converrt this into Dolby Digital 5.1 output using the Pro Logic II decoder. - convert LPCM 2.0 and Dolby Digital 2.0 via optical to Dolby digital 5.1 (using Pro Logic II ) - preferably featuring optical input and output - passthrough for Dolby Digital 5.1 tracks. Can anyone recommend any suitable devices? Not looking for anything too expensive - preferably under £100. So far I've found this and this, which does the same job but only featuring analogue outputs and no official Pro Logic/Dolby Digital decoding/enoding.