A few things at work here. Output is based on input type. In other words, input a stereo signal, and you will get a stereo output. Stereo = front left/right. So if your test speaker was connected to any output aside from the front left/right, you will get no audio.
The Receiver should have each output labeled, although even a 7.1 Receiver won't have outputs for two of those speakers. 5.1 is front left/right, rear left/right, center, and sub. A 7.1 setup also has side left/right.
Having said all of that, all Receivers have the ability to create surround channels from a Stereo input.
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