I'm going to recommend some #DifficultMusic
For you.

Morton Feldman's String Quartet II

It's not particularly complicated music, or overly dissonant or even hard on the ears. But it is between 5 and 6 hours long. In one movement. Without a pause.

And if the thought of spending the same time as a Wagner opera listening to a string quartet isn't "difficult music" then I don't know what is.

Actually it's kind of immersive time stopping music and once you get started it's very easy to lose track