I'm betting that the Bose is NOT designed to work with a powered A/V receiver. I'm not sure about that, but you will want to check the manual.
Here is a GREAT photo (IMO) of the cable you need on an eBay listing...
His system includes an Acoustimass bass module, four Direct/Reflecting Cube speakers, and a center channel speaker. The Acoustimass 10 Series IV speaker system is engineered to fill the room with beautiful sound, not bulky speakers.
www.ebay.com
The cable is a D-SUB-15 pin connector which breaks out to a RCA jack (subwoofer) plus 5 2-wire connections. It almost looks like it CAN hook up to a traditional A/V receiver using the speaker outputs and the subwoofer output.
Hmmm.... If that's the case, it should be an easy connection to your Sony after you get the proper cable. But, yes, you should be able to get this from Bose.
The BULLSH!T is that you bought this in the first place. No proper speaker setup requires proprietary cables. The DB-15 connector and wiring you could potentially make yourself if you knew the exact wiring. But, that's just stupid to need to do.
Normal speakers get wired to your receiver directly.
Normal subwoofers get wired to your receiver directly.
Normal speakers may have cost less, and sounded better.
But, if you can find that cable, then you will be in business. I would talk to whomever you bought the speakers from and ask about that cable. After all, it is SUPER important and should have been with the system.