Now the problem: the delay is not always the same. It also allows me to activate cross-fade, or continuous (gapless) playback through DLNA, which are usually not supported over DLNA. This allows me to have a single instance of Media Monkey running, and stream audio to the whole house + the computer at the same time, in sync.

Usually I end up with 11500ms when everything is in perfect sync. Finally, I stand in between 2 rooms to listen to the computer speakers and Music Cast at the same time to see who is ahead/behind, and make smaller adjustments to the delay in Equalizer APO. Afterwards, I go to the editor of Equalizer APO, add a 'Delay' plugin, and enter a delay of 11000ms. They all start playing in sync, but are about 11 seconds behind the audio of the computer. Then, I launch Stream What You Hear, and send the DLNA stream to my Music Cast speakers. First, I launch Media Monkey and start playing music normally, from the Internal Player. I found a solution to my problem, which requires installing 2 windows apps: 'Stream What You Hear' and 'Equalizer APO'.

Upnp player android with equalizer