Tiring of listening, fatigue, and headache are all symptoms of a problem in your system. High frequency hash and distortion causes these problems. Old or inexpensive digital or solid state cause these problems. These are obvious symptoms of a serious problem. I recommend approaching it as a problem, and not living with it. I have experienced it in the past and once gone, it is absolutely wonderful.
I can listen to my system (digital or analog) for hours and have to pull myself away. The moment I turn on my system I fall into its comforting quiet and bathed in warm beckoning music. Never jacked up or on edge because of it. So many system strive for pulling out detail that they end up with all sorts of harsh artifacts that while not easily heard destroy the comfort of the listener.