The ADAU1781 supports two audio inputs and has two audio outputs, with an equalizer in the middle. Can the equalizer be different for the two channels?
Yes. It's important to note that the ADAU1781 doesn't just do equalization. It is fully programmable in our SigmaStudio drag-and-drop graphical programming software. It supports about 400 audio processing algorithms (including various varieties of EQ) that can be placed anywhere in the signal processing chain, independently for each audio channel.
You can find a list of algorithms supported on the ADAU1781 on each of these sub-pages:
There is documentation for these algorithms available on these pages (currently under construction):
SigmaStudio lets you use these blocks to build up a signal processing flow to fit your needs. Here's an example of using level controls to create a broadcast ducking appliction: