and we fully understand why you found the speakers to be "big"
do it a few more times and have fun when they cancel your account.
What? Amazon lets you return stuff you're not happy with with a few provisos, they'll hardly cancel your account.
I don't see the risk with this. If you can't get the deal as described you return everything unopened (or is there a restocking fee?). My understanding is that you get the full refund lets the shipping as long as the goods are unopened.
The OP seems to have done his homework. If you don't think this deal will work, then ignore it.