Input/output from unsynchronized ADC/DAC
There's no good way to do this via the onboard ADC / DAC. You'd have to trigger the DAC conversion in the ADC interrupt, but you wouldn't be able to get the rates set correctly when using DMA so you'd have to go sample by sample. There's a lot of overhead to that and while it could work it wouldn't leave you with a whole lot of CPU left over for the DSP.

The better solution is to use the I2S or SAI interface with a dedicated audio codec. You can either use two codecs or get a codec that has both input and output capability.