I am the anon who wanted to address 24 DAC chips with shift registers, I have come to my senses and of course the better solution is fewer, 8-channel DACs.
Am I going to have a bad time if I try to send SPI signals over wires from a Pi Pico to a number of "daughter" boards, each with their own serial-addressable DAC? I've read that SPI isn't designed to be sent over wires and will be subject to interference, etc, but at the same time, these would be very short wires connecting boards that are all very close together. And I could use a clock frequency as low as 1 MHz.
The alternative is I put all the DACs on some kind of custom PCB so the serial connection is robust, and then send the DAC voltage outputs over wires. But I'd rather not have to order a one-off PCB for the DAC board.