I wasn't happy with the cheap adau1701 boards. The integrated ADC isn't good, and they only have limited filter capability. I'm returned mine and got a hifiber

I wasn't happy with the cheap adau1701 boards. The integrated ADC isn't good, and they only have limited filter capability. I'm returned mine and got a hifiberry beocreate 4 [1]: DSP + four amps. The adau1451 is much more powerful, and the ADC is pretty decent. As a crossover I use FIR filters, so the four drivers of my small stereo speakers are hooked up to one dedicated channel each. But like with classical crossovers, you need a measurement mic to verify the correct behaviour; unless someone already did that for you. The adau1452 in the freedsp aurora[2] is even nicer (longer FIR filters), I use that for my big stereo speakers. What I really recommend/want is skipping the ADC altogether and getting something that connects the DSP (preferably adau145x) digitally to the amps. Both these devices fall short in the regard, as they feed the digital signal into ADCs. But they're both still really good. Hint if you consider the beocreate: don't use it with a rpi4, that one runs too hot; a rpi3 is perfectly fine for their OS. Once the DSP program is installed you can remove the rpi and use the optical input; or you can use the rpi as the source. [1] https://www.hifiberry.com/shop/boards/beocreate-4-channel-amplifier/ https://www.hifiberry.com/shop/boards/beocreate-4-channel-am... [2] https://github.com/freeDSP/freeDSP-aurora https://github.com/freeDSP/freeDSP-aurora