Where is the subwoofer being sold? I think people are asking because they want to stay clear of the place, not because they "just want to know where you bought it".

People usually ask questions for a reason, but your response would somehow imply the question is pointless or you are trying to avoid answering the question. To this day I don't understand why people try to hide information that isn't helpful for them to hide. Where you considered buying bunk merchandise is sort of important to us, as we don't want to get stuck with junk from that establishment. It certainly doesn't benefit you to hide where you were looking at a broken subwoofer, unless you work there and you took in broken merchandise from a customer that pulls a fast one on you. I could understand not wanting to announce that if you worked there since it would raise some questions about the quality of merchandise that's sold in the establishment.
I'm assuming it's a pawn shop or thrift store of some kind. It's more likely it's a pawn shop because it sounds like something a shady place with some basic understanding of trickery would do. This doesn't imply that all pawn shops are shady, I work for one in fact. However many pawn shops I have been to have exhibited shady behavior in order to disguise broken stuff.