I use an older Nuforce HDP dac/headphone amp. It's an older piece but I love it. It has the larger jack which suits me as I use Sennheiser HD-650 headphones. I would expect using headphones which have the same size plug as the jack on the amp would be advantageous because you eliminate an extra connection.
BTW, what is your price range?
BTW, what is your price range?