What kind of files are they? Nwboater mentions Flac, but I don't see that in your original post anywhere?
I can't help but repeat Nwboater ...
How is your pc hooked up to your receiver? s/pdif, coax, analog, hdmi? Under Options, Audio, make sure Audio Output is set to the correct device. I suggest using Wasapi evnt style.
In DPS & Output format, check Output format on the left (otherwise its not active) and check Channels is set to original or 5.1. Mixing can be set to JRSS, but to test you can try and turning it off (no up or downmixing).
Although you can change settings during playback, certain features require playback to be stopped (not pause). Make sure nothing is playing or paused.
Next, try to play something. Hover your mouse over the DSP icon in the upper right corner (EQ sign). Look at Audio Path, Input, Changes and Output.
If you fail at getting it to work, please let us know what each setting is set to and what type of file it is you're trying to play.