I had to turn mine off to get the lossless bitstream to come through.
I am going to take a look around more on it tonight now that I have more time to see if there is something I missed.
On my Onkyo 606 it only shows DTS if the audio is set to bitstream and secondary is on. With it off, DTS MA comes through.
Edit
Saw this posted over at AVS by boylan13.... This refers only to the HDMI digital audio.
It can be simplified as follows. And these only apply to the HDMI DIGITAL OUTPUTS (not analog and not S/PDIF coax/fiber outputs):
If you set Digital Audio Output settings to:
BITSTREAM with SECONDARY AUDIO OFF:
You get the BITSTREAM Output (Dolby TrueHD, DTS-HD MA full resolution) - ALL THE TIME and Secondary Audio is silent
BITSTREAM with SECONDARY AUDIO ON:
You get the BITSTREAM Output (Dolby TrueHD, DTS-HD MA full resolution) UNLESS there is Secondary Audio (BonusView PiP) or Menu Clicks in the stream, in which case you get lossy Dolby Digital or DTS with secondary audio present
PCM with SECONDARY AUDIO OFF:
You get FULL RESOLUTION PCM Output ALL THE TIME and Secondary Audio is silent
PCM with SECONDARY AUDIO ON:
You get FULL RESOLUTION PCM Output UNLESS there is Secondary Audio (BonusView PiP) or Menu Clicks in the stream, in which case you get 48KHz PCM with rear channel missing (only on 7.1-ch original content) and Secondary Audio is present.