Setting up sound Dolby SPDIF,PCM or HDMI

[kinhell]

I've had a new sound bar for christmas and have been playing with the settings for the Blade 7000 box. Whats the difference between SPDIF, PCM & Dolby HDMI ? Which is best ?

 

[cactikid]

with my vu boxes i just have hdmi to tv and from box to soundbar with spdif.