Looking for a replacement for my 3E Audio DSP board (ADAU1701)

You could try the Zoudio board. It's in the Vendor's Bazaar section. A little different architecture; DSP / Class D amp rolled into one. Limited power, usefulness for you depends on how you listen and your speaker efficiency.

Like all these, it has its own DAC built in, so you need to like the sound of it. I've never heard an ADAU1701 DAC with digital input; only after first going through the ADAU1701 ADC (in a MiniDSP). As an unfair comparison, I like the sound of the TI chips in the Zoudio better - when using a digital input.

I've got mine working with a USB to I2S converter, otherwise BT until they make available USB connect, which I read is working, but with a future release date. You can go fancy as I did by using a JLSounds USB to I2S, in the meantime http://www.jlsounds.com/products.html. I think that combo sounds great!