I have tried with several night builds it's noticeable as soon as the libreelec splash screen appears when booting up.
I will keep testing with more builds until I get the same result as I have with other pc with a gen 7 intel cpu, Even if I try picture adjustments the darker is still more like dark grey.
I also tried with hdmi cables (hdmi 1.4 and hdmi 2.0 rated) and same result shows on both tv and pc monitor. Any how I am a big fan of Libreelec, quite remarkable the work you Guys do, Thanks.
I will keep monitoring these new builds, in the mean time I will keep using the older pc which works very well on this pioneer 1080p plasma. So no rush, just lets enjoy the ride and sharing of experiences, with this wonderful hobby.