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

All in all, there's nothing wrong with your total system. Rock recordings played at HIGH volume is your REAL problem, most of this genre pretty poor recording quality, compressed, no sense of natural timbre. I'd say your system was reproducing these recordings exactly as it should. I don't know that any of my or previous suggestions will help, except those for less system resolution.

Loud rock music played at loud volume is best left for live concerts at large venues.

So I've now listen to a Nucleus vs Innuos and found VERY little difference YMMV. I kept the Nucleus and am very happy.

Uhm what? 25 to 40k budget for a dac?

All you need is a 1200-2000 dollar border patrol dac.

The OP has a top class system, I doubt he wants to go from a DAC with ~22 bit resolution to one with ~10 bit resolution.  

@chayro I live in Malaysia and unfortunately there's no MSB, dCS, Lampizator, Aries Cerat DACs to demo, let alone for in-home demos.

I'm not unhappy, just curious if I can chop off that bright top end with certain recordings. I used to have a Dan D'Agostino Momentum Integrated. I'd use the tone controls and simple cut treble 1 or 2 dB. I don't have that flexibility any longer.

It's just occasionally bright. With 90% of recordings, and at 80-85dB, the transparency and detail are actually a benefit.

Why not just use the equalizer function within Roon?

@deludedaudiophile I tried that and Roon’s equalizer distorts the sound to the point I can hear the difference. Piano sounds off, for example. Having a highly resolving system is a two edged sword.