Audeze Deckard. Discontinued, apparently when Audeze decided to concentrate exclusively on phones, but quite well-reviewed. True Class A, includes a 32/384 USB DAC input, volume control, and three selectable gain settings for different-impedance phones. Build quality is superb. And it even has enough juice to serve as a standalone preamplifier.
If you’re considering $1-2K amps, a used Deckard can be a cost-effective alternative. They’re currently on eBay in the $300-500 range. It’s a shame that Audeze got out of the amplifier business before this model had a chance to build a base, b/c the Deckard could have been a game-changer in its price class.
I paired my own unit with 22-ohm Audeze LCD-X phones for years with superb results -- detailed, palpable presentation, neutral tonal balance, low noise floor, and bass extension deep into the 20-30Hz range. Even after migrating to to the headphone stage of a $19,000 integrated, I still hesitate to sell my unit b/c, frankly, its sonics are hard to fault. My only beef was that it ran as hot as you’d expect a Class-A amp to run.
Here are some reviews / specs: