The chain starts with a CD player (no fm stations at the tip of the Big Island of Hawaii unless you like Hawaiian Music). This goes to a Rockville REQ231 equalizer, and from there to the Rockville RX230 crossover. From the crossover to the stereo and sup amps. Stereo output is from 100Hz up, and sub output is from 100 Hz down. Judging from single channel performance, this worked very well. The purpose of the sub is to keep large cone excursion out of the main speakers.
I assumed that the input options on the Sherwood were all preamp. However, the whole Sherwood business went down in flames when I hooked it up and turned it on. Dead as a door nail. Research showed that it was made in China. Now I have to find an amp on Amazon, which means playing Chinese roulette again. One in twelve failure is about the best you can expect, even with name brands. The current Sherwood is one in five.