Boulder 866 vs Gryphon Diablo 300

I’m looking for some input on an upgrade to my current system. First I’ll list below my current components:

Datasat LS10

Roon Nucleus Plus

ATI 3305 (330 watts x5)

ATI 3004 (300 watts x4)

Kef Reference 3’s with matching center. Kef R3 rears and Kef 8a Atmos speakers.

For those not familiar with the ATI 3300 amps, these are an incredible value. I used to have three PS Audio BHK 300 mono blocks from my front sound stage. I originally bought the ATI 3305 for my rear speakers. I did a pretty exhaustive A/B comparison between the ATI and the BHK and for 90% of the music they were indistinguishable from each other. The other 10% of the tracks the ATI would ever so slightly edge out the BHKs. So needless to say, I sold the BHKs.

To get back to my question. I’m perfectly happy with the HT side of things, but I would like better 2 channel performance. What I would like to add is either the Boulder 866 or the Gryphon Diablo 300. Both have HT bypass, The Gryphon has sub outs, the Boulder doesn’t. The Boulder is Roon Ready, the Gryphon isn’t. The Gryphon has more power and will match my ATI amps better when using everything for HT, but will I notice the difference in power when everything is level matched?

So outside of the obvious differences I’ve mentioned, what are the sound quality differences? For those of you that have auditioned both, what were your impressions on overall sound quality between the two?