Gaz, Not wanting to presume your level of expertise but I already use a HDMi splitter from my V6 box to power 2 TV's.
What I learnt (that no one could tell me) is that you need to turn off both TV's and the V6 box, connect all ur wires and then turn on ALL relevant TV's BEFORE u reboot the V6.
Once this is done (and assuming it all works) NEVER EVER complete power down any of the TV's (leave them in standby mode) as if u turn them off it loses the HDMi handshake and u have to reboot all over again!!!
I'm currently using a powered HDMI splitter as well (not sure if that makes any difference to performance)?