While I wouldn't pretend to be an expert on DTS,
this Wikipedia entry seems to discuss what your player is probably doing with DTS-HE/MA streams:
DTS-HD High Resolution Audio, along with DTS-HD Master Audio, compose the DTS-HD extension to the original DTS audio format. It delivers up to 7.1 channels of sound at a 96 kHz sampling frequency and 24-bit depth resolution. DTS-HD High Resolution Audio is selected as an optional surround sound format for Blu-ray Disc and HD DVD, with constant bit rates up to 6.0 Mbit/s and 3.0 Mbit/s, respectively. It is supposed to be an alternative for DTS-HD Master Audio where disc space may not allow it. DTS-HD High Resolution Audio is implemented as a core DTS stream plus an extension containing the two additional channels plus deltas to enable 96/24 sound reproduction.
My emphasis, for the relevant bits.
Chris is bound to chime in on this one.
