Try some nice open-back headphones if you haven't already - they typically don't suffer from anywhere as much ear fatigue as closed-backs. AKG K240's are one of the industry standards and are inexpensive, lightweight, and sound fantastic (take a look at Beyerdynamic DT990 and Sennheiser HD600 if you feel like spending more). My K240's are coming up on 50 years old and still sound awesome (and I prefer them over my K7XX's).
Mine were about that age when they finally gave up from me too often running over the cable with my office chair.
I think the current K240 Mk2s I recently bought to replace them are not as good as the original "sextet" model.. I now use the K240 Mk2s when I'm playing my keyboard silently and K702s for more critical listening. Both are light and comfortable.