I'm sure this is a basic question, but still need to know the answer.

What's the purpose of the crossover on a subwoofer? Is it used to integrate the sound between the subwoofer and front speakers?

Is using the crossover beneficial?

Here's my set up-

Sony DTR315 Receiver or something like that (pretty basic- does a fine job for me)
Mirage FRX5 floor speakers
Definitive Technology PS80 subwoofer

My receiver doesn't have a sub connection, so I'm running speaker wire from the receiver to the sub and then out from the sub to the fronts.

Can I use the crossover without an connection on a receiver? If so, how? Also, is it worth it?

Thanks a bunch in advance!

I'm glad I found this place.
Eric