Which amp to drive Avalon Diamonds?

Presuming you are fond of the ARC Ref 3 the path of least resistance would be to audition the ARC Reference 210's. They're a significant improvement over the original REF300's. The others you mention are some very best sounding amplifiers available. However in terms of synergy each of the designers mentioned has a bit of a different perspective &/or approach. Mileage will vary on if you feel the amalgamated sound is to your liking.

If time permits please do post a follow-up. I’d be most curious to hear how your final solution turns out.

Cheers,
Bish

I would recommend the 220 wpc Lamm M2.2, as it has double the power of the 100 wpc M1.2. My friend had the Eidolons (not the Diamonds), and he found that having the extra power really helped to get the most bass response from those speakers.

Good Luck in your search.

Bish: I auditioned the Ref 610 & Pass X600.5 and prefered the Pass. I prefer my listed amps over the ARC and Pass. The Ref 610 was great but sound more SS like than I liked. I will definitely keep you guys posted.

Kurtank: I have listened to Terry's system and it was great. I would rather have more Class A power.

I used to have Lamms M1.2 Ref driving my Eidolons Visions. It was not a good match IMO.

The VAC should be holographic and extremely well-balanced on the Eidolon Diamonds I imagine - and would be my personal first choice by far. Having spent a good bit of time listening with the PHI220s on them I have to imagine the 300.1 would be amazing. I can tell you that the VAC 220s were a better match to my ears than the Boulder amp in almost every way (though that likely depends highly on what type of music you listen to and synergies with associated equipment as well).

For what its worth, a lot of people who have lived with the CAT/Diamond combo speak highly of them but I have not had any extended direct time with the combo (I'm sure they will be chiming in shortly).

Will be curious to hear your selection but congrats on what will likely be an exceptionally musical system!