As a reviewer I'm somewhat reluctant to lay bare my impressions of my own gear in the public forums, so I've kinda been holding back in commenting on the ACT2. Nonetheless, having read Valin's remarks on the ARC Ref 3 I was struck by the similarity of some of his observations to those I made of the ACT2 in my August 1st Soundstage! review. (Of course he is a better writer than I.) This suggests to me both devices share at least a few common virtues. Although I've not heard the REF3, I'll take the TAS review as an accurate account of what was heard, and feel not uncomfortable about making comments within the context of publication.
To give but one example: As Valin wrote of hearing how notes from the REF3 linger in space before those that succeed them, I cashed out a similar hearing with the ACT2 in terms of the absence of smearing across the temporal boundaries of notes. This was in a context almost identical to one he mentioned later in his article - that of a piccolo cutting through an ff orchestral passage and rising above. Likewise we offered similar comments about the realistic quality of strings, woodwinds, and particulary the reproduction of the human voice. I found other comments that, in essence, describe the same characteristics though stated differently.
Whereas the TAS article stuck me as focusing (but not entirely) on nuance, my praise of the ACT2 pointed to its facility in the areas of dynamics and timing. It is the relative character of these attributes that for me - at least in my current stage of audiophilia - most distinquish the great from the near great, and are the most difficult to do very very well consistently across the frequency spectrum. And without commenting on the REF3, it is here that the ACT2 is sublime in refinement.
Dynamics and timing are rudiments of musical performance, and the heart and soul of life-like sound reproduction. Analysis may let us divy them, but they are processed synthetically in the hearing - at least that is my phenomenological take. And when a piece of gear - such as the ACT2 - rightly enables this synthesis it offers "that extant magical whatever that hints at the limbic level that live music is afoot".
The sound of gear from ARC and CJ have had differences for over 25 years, since both companies began offering their wares. And in one sense these differences represent a titanic struggle for your sonic soul, if not your wallet. Yin vs Yang, etc. etc. I do believe the house sound from both companies has grown closer over the years rather than more different while neither has lost their inherent character. When it comes to a purchase we each make our decision. Rather than debate which is "better", I am just happy that we have the choice between fine components such as the REF3 and ACT2.