If you want surround sound from your Bluray player and Sky+HD box via the home cinema system, you will need to buy a 3 way manual optical switch and 3 x optical cables.
The Sky+HD box and Bluray player will both connect to the input on the switch via optical cable. Set the Bluray player up for optical (digital) audio out and bitstream in its settings menu and the Sky+HD to "DOLBY D" under optical output in the sound settings menu. Then run another optical cable from the switch's output to the single optical input on the HT-TZ225. Select D-In or similar on the Samsung to hear audio from these external sources connected to the digital audio input.
The HT-TZ225 will connect to the TV via HDMI cable but as you have bluray, you could just use it for all discs and use the HT-TZ225 for audio only and therefore the HDMI cable would not be required. It would be easier to setup if you have the HDMI cable connected though and then you can get rid of the HDMI cable. HDMI cables don't cost much so you might as well connect it up though.
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