7.1 surround sound setup help... rear surround speakers not working properly

Hi Guys,

I am struggling to properly setup my 7.1 surround sound system. I just got all this stuff from my dad, but he only ever had a 5.1 system, I added the 2 rear surround speakers. Here is an exact breakdown of my equipment:

HPTC windows 7, with a GeForce GTX 560 ti graphics card

PS4

The receiver is Pioneer elite 33

Front speakers are Klipsch RF-62

Center speaker is Klipsch RC-62

Surround are Klipsch RS-42

Rear Surround are Klipsch RB-51 (these are the new speakers)

No sub at the moment, it is broken.

What I have tried so far:

When I do a channel test on the Pioneer settings, all 7 speakers produce sound. However, when I try to play a test .mkv file (for example the DTS MA HD test file, or Dolby True HD test file), the rear surround speakers do not work. When it is their turn to play sound, the sound comes out of the surround speakers, not the rear surround. This happened when I play the file on my HTPC. Thinking it may be a limitation of my graphics card, I played the file on my PS4, but have the same result, with the surround speakers playing the audio during the rear surround test. When I played it on my PS4, it was through plex, so that may be an issue, but I am fairly certain plex supports 7.1

As far as I can tell, my receiver is setup properly, and my equipment should be able to handle everything.

Next I am gonna try and get a bluray that has 7.1 DTS: MA or Dolby TRUE HD, to see if that format plays 7.1, but I don't think that is the issue.

Does anybody have any further ideas of things I can test?