RME ADI-2 FS DAC. Not so much of a Dark Horse, but the balanced DAC XLR output to a good amp (tube or otherwise) is under-rated and can be close to the best I've heard. The flexibility to change the EQ, balance, loudness, and other exotic adjustments along with presets gives you different flavors at the digital end before you pass the signal on. You can tweak forever or just listen bit-perfect. The headphone amp itself is just OK, with the exception of the 3.5mm IEM port which is very good. Best for sole use as a DAC to downstream amps/preamps. Lately, my favorite pairing has been to a B&K ST2140 power amp - balanced via XLR inputs to the amp.
Dark Horse DAC
Doge Dac 7 MKII is probably not on your radar. Maybe it should be.
(52) Doge 7 Tube DAC Review ! The Best DAC Award 🏆 - YouTube
I took a chance and decided to buy it. Not completely broken in, but already
performing way beyond expectations. Check out the Doge website and read/watch the reviews. For me this DAC is a game changer. Comments??