I think I found a silver lining with the whole distant vocals issue. I was listening to a favorite album of mine, and suddenly found myself with goosebumps. Every other time I had heard a certain song, the vocals were SO forward that it caught 90% of my attention. On the Qs, it balanced out, and I heard things I had never noticed before. The swell of the strings made me feel like I was rising and falling with the music.
I think for that reason, I'm probably going to keep them. Although the 598s will likely remain my primary cans, I find it interesting to hear songs a whole different way, if not always the way I prefer. Hopefully I can add another amp to my collection soon and then reevaluate the Qs.