As I told before, I'm in the mood to tune any HF radio station and therefore I need to get some audio out the Zynq-7000. 

To get some audio out of the Zynq I examined a few options:

1. send the audio stream to the PS (via DMA or Data Capture) and then:
   1. from PS to a Python client (the same I'm using to display the wide spectrum) via a web socket stream
   2. or from PS to a DAC via I2S 
2. get audio as a digital stream from the PL (via I2S standard) to a DAC (PCM5102 or similar)
3. get audio as a PWM from the PL (as Raspberry does)

In the future I'd love to avoid the use of an external PC, so I discarded 1a 

I discarded 3 because the audio quality is not excellent and you can hear some "clicks" 

I discarded 1b because I'm not very fond of linux drivers and it is not very clever to move audio from PL to PS and then back to PL

Therefore the winner is: get audio as a digital stream from the PL (via I2S standard) to a DAC (PCM5102 or similar): 

• I2S is a standard
• several very cheap I2S DAC exist (PCM5102, MAX98357, ...)  
• I found a Vivado IP that worked immediately. See I2S in the Details.