Popular DAC that is known for its warm-ish sound?

TEAC NT505 has the sound you are looking for. Concerning support, all the manuals, drivers, firmware are all on line to download and in English. Onkyo is providing US support, distribution and I assume warranty issues. It is very new in the US and I think support from Onkyo may not be 100 percent in terms of product knowledge. You can purchase through Quest for Sound. They have a web site and I purchased mine from them. Great place to deal with. I'm very happy with the DAC and it's chip, Verita AK 4497. High end chip same used in high-end Esoteric DACs. My only complaint, it is not yet Roon certified. It does provide MQA unfolding, great Bluetooth connectivity, network and USB ready along with coax and optical. Provides both balanced and unbalanced in/out taps along with very high DSD upscaling. The price is very reasonable.

Border Patrol DAC is "warm-ish" with the standard tube, more so with a Mullard Great Britain EZ80.  I primarily listen to analog. I have a analog bias.  The Border Patrol moves digital music closer to analog.  Can make a CD sound very nice.   I also like my Schiit Yggy - decreased warmth but more detail. These two DAC's have turned me off on my Benchmark, Oppo, and W4s DAC's.

Audio Note pricing can be hard to find online. Best to contact a local dealer for more information.

Whay do you want DAC sound warm? I would rather have a neutral DAC, plus some sort of warm Amp (pre-amp).