I have an old passive Boston Acoustics 595x THX sub, it just has standard speaker wire terminals on the back (one set). And I have a Sony STR-DG800 receiver, but it only has the RCA-style connector for a Subwoofer, rather than the standard speaker terminals it has for the other channels.

Can this sub be hooked up to this receiver? Do I need to piggyback the sub's speaker wire onto the Front L and R wire terminals, or do I need some kind of adapter? Or is my (rather cheap) receiver not designed to power a passive sub?

Thanks,
R

Your receiver cannot work with a passive sub. Passive subs need an amp. Your receiver does not have a spare one of those. Not to mention, the ones yuo do have lack the power needed, and aren't wired to be fed the right signal. You could look into getting an amp, but it might be cheaper (or at least more useful) to just get a powered sub.

That's what I figured, but I was naively hoping since my other speakers are also passive (by definition, I suppose) and receive amplification from the receiver, there might be a trick to get it to power the sub as well. Oh well, worth asking. Thanks for your reply!