Looks like the links that dani olivares provided aren’t working any more. Here’s another very similar product on Amazon:
https://smile.amazon.com/dp/B0002J226O
Or, if you need a built-in subwoofer crossover and level controller: https://smile.amazon.com/dp/B07D6JTD4V
For a few bucks more, you can get an equalizer with multi-amplifer level controls and outputs: https://smile.amazon.com/dp/B00JZQYX2G