i'm not able to receive 5.1 sound on some movies that are supposed to be in 5.1 i get sound but it's very low and mostly just the subs rumbling, just like the sound you get from commercials that aren't in 5.1 while watching a 5.1 program, like NFL football, for instance. it happens a lot on channel 74 (uhd) on directv for some reason. for instance, i recorded scarface in hd and my receiver says it's in 5.1 but it's obviously not. can anybody shed any light on this? thanks.