It sounds like you might have some noise sensitivity along with your tinnitus? If you have sensitivity, fatigue, and tinnitus, it's a good indication that you have a hearing loss. Have you seen an audiologist? If I just described you, then I know what you are going through from personal experience. I would stop, take a breath, and consider a different path via your audiologist.
But the short answer is... yes, the HD 600 has more sparkle than the HD 650, but remains a very non-fatiguing headphone. I think it's a great choice given your conditions.