Which DACs are known to be sweet/rich/relaxed?

All systems depended, on who can tell anyone how something will sound in their system. Room (huge) and then what gear used and their mix and matched, power cords used (huge),  Good quality well made DAC from companies that built from the ground up and not using OEM part to build it, this also makes for better long term use problem free. Lastly, a bad recording is what it is is, no matter the format it sucks,...Smile! 

@robert1976 Rob, I think you’re on the right track - addressing room acoustics is extremely important and without getting that done you’ll be chasing ghosts by swapping your components. I just started paying more attention to it as well and it is already paying off. Also, once your room is more or less tuned consider experimenting with network switches and filters. Depends on how sensitive the Tambaqui is to the quality of the incoming Ethernet signal, you may further improve the sound of your system as you run your Ethernet cable directly into the Tambaqui. I know it’s somewhat a controversial subject and I’m potentially opening a can of worms here by bringing it up, but it can help further improve the presentation and let your digital components do what they need to do much easier without having to deal with the electrical noise, RFI, EMI, etc. You may be surprised by the improvements. Again, depends on how your digital components deal with noise and how noisy your router is.

Some additional info and education on the subject with few examples here…

Network Acoustics Eno

Network Acoustics Muon

The sound of network switches

I have the Scala Utopia, which, offers somewhat similar challenges as the Stella Utopia (albeit on a smaller scale). It sounds harsh and revealing with some equipment.

After a lot of experimentation, I’ve settled onto this for musicality:

1. A basic $5k R2R DAC (Holo May)

2. (Very important) a musical, euphonic preamp (I’ve had McIntosh tube preamps before but nothing beats my current Hegel P30. Feels like I am using tubes but with none of that noise / distortion at higher volumes)

3. (Very important) ‘warm cables’. I moved from silver-based power cables to copper based ones (AQ Hurricane)

4. Hegel H30 amp to match my preamp

Very musical, with ‘meat on the bones’ type presentation.

I have a Roon Nucleus Plus, with an Ayre Acoustics QX-5 Twenty DAC, Pakedge switch, top end shunyata ethernet cables, Audioquest power cables, JPS Labs speaker cables, Revel Salon 2 speakers, powered by an Hegel H390 integrated and an Audioquest Niagra 3000 line conditioner/ surge protector.  The sound quality I'm getting via #1, Qobuz, Tidal and from my internal hard drive is extraordinary!!!  But, the greatest and most crucial contributor to the stunning sound quality I'm getting out of my system come from my Reference level Ayre Acoustics DAC.  All associated equipment that makes up a top notch streaming system in order to achieve the best sound must be...."Top Notch."    Roon Nucleus  included.  No more cd's or vinyl for me.  Just me and my lovely iPad.  Ain't life grand!!!    

I forgot to mention that my Ayre Acoustics QX-5 Twenty DAC is a streaming DAC.  I use the DAC as a  streamer  My DAC along with my Roon Nucleus Plus renders amazing and marvelous results.  I am overwhelmingly pleased with this combination.  Before opting for the Roon Nucleus Plus, I went through an extensive auditioning process that included most of the high end brands servers, streamers, in various combos there of.  After hearing the Roon and a stand alone DAC in a system at one of my High End Audio dealers, and after being absolutely floored by what I heard out of that system, base on that, I decided to configure my system in the same manner.  So, the Roon was the right solution for me and what I desired to accomplish in my own system and I've been very, very happy with the results.  Well, to each his own.  So glad I was able to find my little slice of audio heaven.  Happy listening.