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

@robert1976 There's nothing wrong with your DAC it's the Nucleus.

Get a decent streamer/server, preferably one you can attach a master clock to, like Aurender N20/N30 or similar.

Many rock recordings have a hot top end. Ever been to a rock concert? An accurate DAC should be transparent to the source. If it adds its own sonic signature it is POOR quality - and not worth using. 

Thanks @lordmelton, I should do in-home demos to see what a difference that makes.

I remain a bit sceptical because Stereophile said about the Nucleus "JA found that the sonic differences between the Nucleus+ and the considerably more expensive Innuos Statement server were small."
https://www.stereophile.com/content/roon-labs-nucleus-music-server

Also, Jay's Audio Lab found zero improvement with his MSB Select II between streaming from his laptop and using a Taiko Extreme: https://youtu.be/k0SDLQJDrG4?t=199 

I suspect it's highly system dependent and should be tried in one's own system. Which is what I'll do. Thanks again.

@jasonbourne52 Isn't that a highly personal thing? Not everyone aims to get as close to the "truth" as possible. They might prefer a slightly more relaxed presentation because that allows for longer and more easy going listening sessions. By definition, all recording equipment, audio components, and rooms add distortion and colouration. Nothing wrong with wishing to mellow things out a bit if you're in a large untreated room.

Hi Robert, reviewers get paid to say nice things. It takes a long time to build a great system, do your own comparisons and listen to DSD files if you can.

You already have great components they are going to need tweaking to get them sounding their best in your environment and for your taste.