Hi Ez_bois243,
Yes the Stereo mixer of Toppobrillo will give you good mixer possibilities, absolutely however it's not an audio (input/output) interface as such. On the other hand if you feel as comfortable as Kel to leave it out and you can handle it directly on your mixer then that's fine of course as well. As mentioned it was just a thought :-)
Enjoy your modular and kind regards, Garfield.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads