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

Another vote for an Acoustic Research solution. In my case I replaced my Esoteric K03Xs because it was sharp on the leading edges, no matter what cables amps preamps or speakers. I was lucky to find an AR Ref CD9. This is an all tube affair and significantly fixed the problem I’d had. All of the highs became clear transparent and never harsh. I use the DAC for streaming via coaxial and find it so much better than the onboard DAC in the Pioneer N70Ae.

The CD9 plays into a SS AR LS10SE and Luxman M900u to a pair of large horn speakers with super tweeter. No harshness or sibilance at all but lots of airy highs.

Another vote for an Acoustic Research solution. In my case I replaced my Esoteric K03Xs because it was sharp on the leading edges, no matter what cables amps preamps or speakers. I was lucky to find an AR Ref CD9. This is an all tube affair and significantly fixed the problem I’d had. All of the highs became clear transparent and never harsh. I use the DAC for streaming via coaxial and find it so much better than the onboard DAC in the Pioneer N70Ae.

The CD9 plays into a SS AR LS10SE and Luxman M900u to a pair of large horn speakers with super tweeter. No harshness or sibilance at all but lots of airy highs.

Good to hear some other folks own an Audio Research Ref CD9se… an incredible DAC that gets the details and nuances in order with exceptional balance and musicality.

Mine has really profoundly influenced the sound quality of my system in all the right ways.

I'll probably be castigated for this recommendation.

Before you do anything, install a dedicated grounding system and connect it to every metal case with a separate lead back to the grounding point rather than creating a daisy chain between pieces of equipment.

That should make a massive improvement, but to completely fix the issue, you'll need to do that same with all speaker drivers. Sometimes just grounding the frames or baskets isn't enough and it's necessary to also ground the magnets.

It that fails, then and only then consider changing equipment.

I’m going to re-iterate that changing your front end streamer is most likely to take away the edginess with your existing excellent DAC.

The aforementioned Grimm MU1 is my favourite for achieving this and it’s all in one box with the Roon "NUC" included in the tin (so you don’t even need to worry about finding a separate Roon Server).

It’s a stunning piece of kit.

Someone mentioned earlier that they replace their dCS stack with it.