New on the market is the Furutech ADL Stratos, or the older (and cheaper!) GT40 model. It's a headphone amp and dac, plus analog inputs and also can serve as ADC to convert your vinyl to digital if you so desire. I don't have any personal experience with it, but the vinyl ADC capabilities are intriguing.
If you're only going to run planar headphones, you don't even need a dedicated headphone amp. A regular integrated amp will work just fine. Either run the headphones off the speaker taps directly (if the noise floor is low enough) or use the jack in front which is likely just a resistor in series; planars don't really care about that, whereas dynamics might behave a little oddly.
