Thats an great achievement :-)
Im looking into making a DSP based on your components and findings, are your github page up-to-date with current revisions? Im looking at uDSP combined with DAC-AK4458 and ADC-PCM4202 with differential inputs.
Designs you are looking at are update to date.
Both the DAC-AK4458 and ADC-PCM4202 work very well, with hardware control. Even though the DAC-AK4458 is a newer design it is in use in my crossover box - it just works and sounds good!
The uDSP is a smaller version of an existing design, simplified quite a bit. Initial testing is all good, not used it with bigger boards but no reasons it would not work. Only difference is losing the signal-ground-signal-ground arrangement on the I2S cabling, which could be an issue if you run long (say >5cm) cables.
An electronics engineer and a long term electronics hobbyist. I like tinkering with stuff and making things.