I own an REF 9se… (technically a CD9SE). It is the best DAC I have ever heard… I had a Berkeley Alpha Reference 3 ($22K and highly rated) in my system with my ARC 9SE for several weeks… I fully expected to be coming up with another $5K for the Berkeley… but honestly the diffference was absolutely minuscule and tipped in the favor of the ARC… a tiny…tiny more flushed out sound.
I was pretty shocked when I heard the ARC… and went back and read reviews of previous models. They are very highly rated… so, I am sure there is not a huge differences between models. Tne strengths of the ARC is musicality, fully fleshed our sound that sounds natural. The detail is all there… but not pushed in your face… but very realistic. The 9 is definitely world class. I find it hard to believe the 8 isn’t relatively close. I have heard great things about it.
However, some folks want a lean, details forward sound… that is not ARC. You can see my system under my UserID. The ARC DAC… is simply amazing and completely complementary to the other ARC stuff to produce detailed musical sound. Obviously the sound I have been going for for decades.