In 2017 I designed and prototyped a custom 9-channel A-to-D converter using the amazing Cirrus/Wolfson WM8235 9-channel analog front end, http://www.mouser.com/ds/2/76/WM8235_v4.2-532446.pdf. But I was unable to find the right setting for their 300 configuration registers that made it work as a normal A-to-D converter, and their tech support would not respond to inquiries. The remnants of that suspended project are here.