What you’re talking about is known as a two-channel electronic crossover, a common pro-audio component. Depending on your price range and the quality of your equipment, you might check manufacturers like Behringer, Rane, Ashly, BSS, Yamaha, TDM. Many of these manufacturers are now making digital components, so if you’re looking for analog you’re relegated to their legacy products.
The caveat is that your integrated amp must have pre-out and main-in jacks in order to utilize any outboard processor.
Regards,
Wayne A. Pflughaupt