using Acoustimass® 10 speaker without a receiver

im trying to understand something here....do i need a receiver to use this or could i use a rca to 5.1 surround sound decoder box?

First off, here's the owners manual for your unit.

Looking at the connection instructions,you'll need a full receiver with five amplifiers and speaker level outputs and one (what appears to be) a RCA subwoofer output.

If you got this setup used, I really, really hope you have all the connecting cables. Without them, you're kinda boned and will have to get them directly from Bose.

Good luck