DTS HD volume really low

Hi there, I'd be really grateful for some advice please. I have a marantz  SR-7300 receiver and a samsung blu ray BD-C6900 player. I am using the players Hd decoder by running the 7.1 connections. The problem is this: Dolby TrueHD discs sounds fabulous and powerful. But when I play a disc which is mixed in DTS HD, the volume lacks a serious amount of oomph and the effects seem somewhat muted. I've played with all the settings (PCM, stereo etc) but nothing changes. The blu ray players is compatible with DTS HD also. Any ideas please?