Unidentified device under diningt seats

[Chester B. Stone, Jr.]

While exploring my recently acquired 2001 Newell, I discovered an electrical device under the dining seats. It has the markings a/b/s/ 335is.2 and it has a set of factory installed speaker wires as well as what looks like 12v power wires and a blue wire. I have attached a photo. From prior postings, I suspect it has to do with a subwoofer. Would appreciate any information as to what it is and how to use it. I recently replaced the factory amp with a Sony surround amp with optical imput.