I agree with Ckoffend that the Kora Hermes is a nice-sounding DAC, especially with NOS tubes. The tubes would be key to getting the warmth you want and for that I'd try Mullard or Amperex.
Another one to listen to would be the Apogee Mini-DAC. Warm and full-sounding if your software has it, lots of detail and good harmonics, and personally I think I might take it over the Kora.
Another one to listen to would be the Apogee Mini-DAC. Warm and full-sounding if your software has it, lots of detail and good harmonics, and personally I think I might take it over the Kora.