I get fatigue very easily if the gear is fatiguing or the room is fatiguing. I would check you room first to see if you have too much sound waves banging around in there.
If you room passes that test and you still have fatigue then it is your gear. I have tried a lot of gear recently and the most relaxing and smooth gear has been the new Class A KRELL XD amps. I do not think you can get fatigue from this gear, as much as I have tried.
The KRELL K-300i integrated is amazing. I sold it to buy the KRELL DUO 175XD. I am going to sell or trade-in that 175XD for a more powerful XD amp. If you can find a K-300i jump on it. I spoke to a KRELL dealer recently and he said the K-300i integrated is selling extremely well. I also owned the CODA CSiB and preferred the KRELL K-300i (smoother).
My issue now is that I listen to way too much music. Not sure how long my ears will last at this rate. For example, yesterday I started at 8:30AM and finished at 2:30AM. The last 5 hours were with headphones.
No fatigue at all. I used to get a lot of fatigue before I sorted out my room acoustics and gear. It was mostly the room causing fatigue with my 2-channel and the gear for my headphones. I now use the KRELL amp(s) for both.