Any speaker terminal passive crossovers?

I had a pre-amp with a line out for the subwoofer. I used FMOD passive crossovers to keep certain frequencies from hitting the sub. I changed preamps and the new preamp does not have a line out for the subwoofer. I now connect the subwoofer to the speaker terminals of the amp, which I think sounds better, but I would like to find a passive crossover, like the FMOD, that would connect to the speaker terminal. Any such animal?
Why not just give your new preamp an additional line out by using a Y-connector? And why do you need the FMOD? Powered SW generally have their own low pass filter.

However..I assume that your SW has separate terminals for hookup to speakers. If so, inside the SW amp there is a voltage divider that attenuates the speaker signal so that it looks like a preamp output, and then this signal is connected to the line level input of the SW. To use the FMOD you would need to put it inside the SW (after the voltage divider) or you could duplicate the voltage divider outside the SW and connect the attenuated signal through the FMOD to the line in terminals of the SW.
Good idea Eldaford; however, won't a Y-connector affect the signal by adding something else in the chain? Yeah, the sub has its own low pass filter, but the FMOD used to cut things like vocals even before it got to the sub. It gave me cleaner lows, or at least I thought it did.

Your method sounds too much for me to handle and I would probably end up messing up the sub. I don't know if I will try it.

I thought it was worth asking.
Matchstikman...The Y-adapter will do nothing more than what your old preamp did. (It had a built in Y circuit).