Just replaced my old pi / hifiberry setup with pi 3 and hifiberry DAC+ pro which is connected to the network through a wlan stick.
After a while, I got stuttering sound, I did not get through one song without issues, regardless the file format.
Finally, found the solution (at least no more issues until now), seems to be a power management issue related to the chipset rtl8192cu which is used in the wlan stick I have (zyxel nwd2205), after implementing the code below, playback is fine.
[i]Make a file 8192cu.conf in directory /etc/modprobe.d/ with the command
sudo nano /etc/modprobe.d/8192cu.conf
and add the following lines
Disable power managementoptions 8192cu rtw_power_mgnt=0 rtw_enusbss=0
Hope this solution helps others as it took me a while to find it.