Tube Amp w/ Zero DAC

Budget for this purchase is $200-550. Looking for a solid tube amp, preferably one that starts off pretty good, but gets great when you roll the tubes. I would like it to be good now, with room for improvement when I get ready for a new project. Preferably new, but I could potentially be convinced on used, so bring it on.

As far as signal chain, I've got an HT Omega Claro Halo XT sending signal to my Zero DAC's Optical. *Insert Tube Amp Here* Using it to drive Audiotechnica ATH-A900s, Grado SR225s, and Sennheiser HD595s. If I'm feeling risky, I may use the same amp to drive a pair of LCD-2s or HE-500s in the eventual future. The Grados may get a recable in the future, but assume stock, if that makes a difference.

Musical taste is as wide as possible. I listen to classical, jazz, post rock, punk, metal, hip hop, acoustic, dubstep, pretty much everything. I have cans that pretty much run that full gamut of styles with their sound signatures. I would like an amp that would compliment and possibly even out all of my cans, if that's possible.

Thanks guys, and I always trust your judgment.

The Lyr is a hybrid amp, right? Also, with the impedences of all of my cans being so low (all below 50) what considerations should I make to avoid getting something too powerful for them?

Also, footprint is a bit of a consideration. It's not a huge deal, but something that could sit atop the Zero (I believe some Little Dot amps would fit, other suggestion are welcome) would be an added bonus. I'm not totally against something with a larger footprint like the Schiit, but the same size as the Zero would be sweet.