Sound Quality of Direct TV audio

I recently put a 1/3 octave spectrum analyzer on my Direct TV audio outputs and was shocked to find that they are brick wall filtering all low frequencies below about 150 Hz. Not a gentle roll off mind you, everything from 150 Hz down is gone.

I thought they were supposed to be delivery "high quality" audio. Anyone else discover this or am I getting something unusual?
Dish and Direct TV share some satellites, so I would expect the same performance from either one.

That said, what kind of receiver do you have? Maybe its just not that good.
You mention you put the analyzer on the audio outputs of the DirecTV, which implies analog type outputs. That being the case, I wonder if the digital stream, either via HDMI, Toslink Optical or SP/DIF are carrying a full spectrum signal.

Any chance you could try the analyzer on the pre/processor outputs to see if the brick wall is there as well? In that event, we could rule in / out whether they're stripping the spectrum or just doing something with the analog output section of the DTV box.
"11-02-15: Philjolet
the current DirecTV does not use RCA outputs at all, only digital"

That's not true. It depends on what receiver you buy. Also, if there were no analog outputs, how was the OP able to take his measurements?