In short, I've connected my Twitch to an amp and 2 speakers. Music only plays out of one speaker.

My setup:
- Mac OSX 10.8.5
- Twitch is connected to a QSC RMX 850 amplifier using RCA connectors from the booth output on the Twitch to the 1/4" Channel 1 input jack on the amplifier.
- The speakers have 4 connectors on the back of each. I've run two strands of speaker wire from each speaker to the amplifier output connectors. So for the right speaker, one speaker wire is split into + and - for one pair of connectors. Another wire is split into + and - for the other pair of connectors. Then on the + output terminal on the amp, I've connected both + wires together to make the connection.
- For the speaker wires, I've cleanly stripped the ends on each to make solid connections. The lengths of the wires are also equal.
- I've double checked that for the speaker not making sound, the speaker wires are solidly connected.

When I begin to play music, sound only comes out of the speakers that are connected to the Output 1 terminals on the amp. And even weirder to me, I can remove one of the RCA booth plugs and continue playing music out of one speaker with just one RCA booth plug connected.

Any advice?
What other information I can share that could help in troubleshooting?

Many many thanks in advance