Hi, I think before you take further tweak, first you should make sure that you have true surround file to test and not stereo audio file. To check if the file are true surround:
[testcase@fedora]$ aplay -D pipewire sample-sound-file.wav
Playing WAVE 'sample-sound-file.wav' : Signed 24 bit Little Endian in 3bytes, Rate 48000 Hz, Channels 6
For surround 5.1, it will have 6 channels.
After making sure you are using the right file, you can play it with your current media player and open also easyeffects. Then use
qjackctl > click Graph to check if easyeffects it self support sorround file. If easy effect from Graph
qjackctl only showing two channels, than you need to map it manually by dragging a line to your audio sink (make it double for example FR to FR and RR, FL to FL and RR, FL-FR to FC and LFE).
The other scenario if easyeffects support surround file, it will have 6 channel on Graph (FR FL RR RL LFE FC) and it will mapped automatically. If this the case, then your file you have now (you mention on above post) must be stereo file and you need to map it manually from audio player to easyeffects then from easyeffects to your audio sink.
I believe there also a way to up mixing stereo file to more than 2 channels with pipewire, but it’s confusing. It’s lot easier to use
You can download surround file from here.