If your object is surround sound then you would definitely need an AV receiver. You could use an AV receiver in multichannel or 7.1 channel stereo mode for distributed audio too. Make sure it has a mode that does this.
Your can also use a stereo receiver or integrated amplifier with a speaker selector box. If the speakers are different then you would need one with volume controls to compensate for the level differences.
So if I used a 7.1 amplifier that had a mode to turn surround sound off, would all 6 speakers still work at the same level?
Just wire them together mate 3 to the left speaker out ,3 to the right.
Cut all the speaker wires to the same length irregardless of where they're positioned to remove any audio latency issues.
Be sure your amp is up to the job & the speakers are identical models.
If they're not ,as americanaudiophile suggest a 7.1 amp will do the job when set to stereo - allowing different impedances & response rates/volumes but is a lot of money & setting up.
Ohhhhk! Got it. So would it be easier to buy another pair of speakers so I would have 8 identical speakers and get a 2 channel receiver? (2 tied together for front left, 2 for front right, 2 for back left, 2 for back right)
You can't just wire up that many speakers in parallel. It would blow up any stereo receiver unless you use a speaker selector / impedance matching box to maintain a safe resistance. http/www.amazon.com/Monoprice-109995-4-Channel-Speaker-Selector/dp/B00DIGD604/ref=sr_1_7?ie=UTF8&qid=1439054400&sr=8-7&keywords=6+zone+speaker+selector
Make sure that you don't have more power than the switch can handle with the protection circuit on.
You could connect them in a series parallel combination but that would change the levels of some of the speakers.
Most surround receivers have a mode that plays all the speakers in stereo at the same time. The levels are adjustable in the speaker set up menu of the receiver so if you want them the same level you can do that. If the surround receiver has an auto set up mode don't use that, set the levels to 0 for all channels (except center which you would select as none) manually.