Since everyone here has been super helpful, I wanted to ask for advice on purchasing a dedicated headphone amp.
I currently use the Dragonfly Red as a DAC/Amp at work, and while I love it I think I could probably get better sound by using the Dragonfly as dedicated DAC and running it into a standalone headphone amp.
My main set of headphones are Beyerdynamic T1 2d gens. I will probably also use the amp to power my Hifiman 4XX and Sennheiser 6XX.
My budget is flexible, part of my question is whether its worth it to invest big money (over $600) in an amp -- the consensus is that there are diminishing returns.