I'm still researching this but though I'd post asking about experiences. Looks like st.com offers a variety of STM32 Discovery dev boards for ARM CPUs to, among other things, play with DSP. But searching this forum didn't find much.
Ideally I'd like something with built-in stereo ADC/DAC but I don't seem to see that. I see daughter boards that have stereo mics and stereo outputs. But mics are a non-starter for me. I need line level inputs.
Or this video recommends a Wolfson board which you splice to the STM32.
What's the difference of the M7 core over the M4? Where to order? How do you power the board?