First try going to setting
and see what the audio
is set at. Is it 5.1 or stereo?
This should check to see if the problem is in hardware (below)
First set the audio
to stereo in setting
and see if you can get sound.(in the roku) Try hooking the White and Red
cables to you TV or/and HDMI cable to you TV directly and see if you can get sound (make sure the sound it turn up and on the right input channel) You should get sound since its hook up to your TV directly and the audio
is set to stereo, if not check the cables, and you are on the right channel.
You said that you have a problem with your Pioneer VSX-94 receiver. I think you said that you have your audio and video running through the HDMI that is hook up to your surround system. I had a similar problem when I was trying to get 5.1 sound. The problem was withing the settings of the surround system.
I'm not know about these types of systems, but I do know that the setting are key. On my I had to change the setting so it knew to get the 5.1 thought the optical input. If you were able to get stereo before and are not able to get 5.1 then it might be problem with a setting. Also I'm not to sure what you are saying is your problem.
Below is the closes manual to your box I can find, it might help. I was only able to find the Pioneer VSX-94TXH. Unless you forget to add the TXH to the VSX-94.
http://www.pioneerelectronics.com/pio/p ... ns0807.pdf
PS. Check for lose wires. You speakers wires might of came lose or some other cable.