eac3 surround sound won't play properly on my PC

I am not bitstreaming.
Just a PC, with a DVI monitor and 5.1 speakers (green, black, orange jacks).
In Realtek Audio Manager I can hear each speaker when I press it.
Video files with AC3 surround audio work just fine, it's just files with EAC3 that sound wrong.

Main issue is that dialog is too low or far while music and effects are too high.
If I switch my sound system to stereo the problem seems to go away, it sounds normal but there's only stereo of course.
At first I assumed it was just encoded wrong, but I recently encountered a totally different video file with the same audio issues.

I installed K-Lite_Codec_Pack_1526_Standard yesterday and the problem persists. Audio seems to be handled by LAV.

Here's a file with this issue (189 MB)
https://www.dropbox.com/s/6iymtv2xve4ls6o/sample.zip?dl=0
At second 46 you can already hear the problem (hopefully)

Unfortunately the audio is simply encoded this way. The center channel (which contains the voices/dialogs) isn't loud enough compared to the four surround speakers.

The solution is to increase the volume of the center channel or lower the volume of the surround channels.

First solution that you can try is this one:
MPC-HC options > Internal Audio Switcher > Enable Custom Channel Mapping > 6 inputs > For "Front Center" add a check in columns 1/2/3
This should send the audio from Center channel to the two front speakers as well. I don't have a 5.1 system right now, so I can't test if this works and sounds good.

The other solution is to actually adjust the volume of the individual channels. You can do that with AC3Filter or ffdshow audio processor. Both are included in the Mega version of the pack.

Are you saying that the file in question is encoded poorly? (that's what I thought before I encountered another video with the same issue)
Or that all files using surround EAC3 have this issue? (on a PC using K-lite)

It is not a poor conversion. The audio stream was originally created this way.

It is not a problem specific to EAC3. So not all files with EAC3 have this issue. But it is a common issue with AC3 and in particular EAC3 tracks.

Thanks for all the answers!

Do they play properly on other hardware without channel adjustments? (external players, bitstreamed to audio systems)

Any keywords you can give me so I can read more about this topic?

You can search for "EAC3 low voice volume" to find more info.

External devices such as receivers often have an option called "night mode" or something similar. That adjusts the volume of the input channels and performs dynamic range compression (also called volume normalization). That is reducing the relative difference between the soft and loud sounds.

Probably the easiest solution is to just downmix to stereo when watching a series that has this issue.

Well, I finally figured out my issue while watching a movie with DTS audio also exhibiting the problem.

Turns out my center speaker jack wasn't plugged in properly, that's why the volume was low in surround setup.

It's fine now.

Sorry for drawing strange conclusions with my limited testing.