I am an ME but I occasionally dabble in EE and audio diy.
I am not sure what you are trying to accomplish but if you let us know maybe someone can suggest something off the shelf. There is a ton of stuff to do this sort of thing and sometimes the names are not logical for said devices.
I assume you have searched through parts express. Also, you can do just about anything in the minidsp devices with the right plug in. Mini dsp would likely be overkill but they are cheap and fun to play with
you can basically mix, level shift, and eq if you want anything with one of these:
https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4