Hi, ive connected my sky HD box via HDMI direct to my amp, then of course from the amp to the plasma, ive also got my sky box connected to my amp with an optical lead, but im only getting pro logic & not 5.1 etc so obviously i have to do some sort of setting letting my amp know? if i unplug the HDMI lead from out the amp i get 5.1, my amps the pioneer lx70 any ideas as to how i change this setting? Thanks.