DACs that do well without a preamp

a DAC that uses transistors, or tubes for the output stage is not passive, it may not have gain like a preamp, but it's still has an active device for the output.

While that may be true, many of them do not provide enough gain to fully drive an amplifier, which is the primary issue in many cases.  Active or not. 

Running a dac direct especially at $2k not good even high end it’s sonically better sounding with a quality preamp section . In a preamp Alps pots, or Bourne are $25 and loss of detail is for sure ,that’s why I avoid any integratedthat has these,a silver round attenuator is what to look for. ,a horrible cheap way out  but used by 70% of the industry it seems , a good resistor ladder shunt type  ,relay control or linear Type  , are Night and day better and  in higher end equipment.

RME ADI fs2 with Teddy Pardo linear power supply. I use this and don’t miss either of my preamps, which are a ModWright LS36.5 and Sonic Frontiers Line 2 SE. Been running direct and have not gone back but will be here soon to compare in more depth. The RME without the Teddy Pardo, no I would not go direct to my amp, as it’s a little thin by comparison but the Teddy fills things out.

I use and completely love the Pontus II DAC, and at $1,730 it's an absolute steal. That said, I've only used it with a pre-amp, so no comparison for you