Best AMP for Avalon Eidolon, ARC, CAT, VAC..?

I think it is very hard to make any specific recommendations, given different tastes, room setups, completely unpredictable interaction between components, etc. So, at best, we can recommend items for you to try in the hopes of achieving what you desire.

I am a bit surprised that you found the Eidolons to be cool and lean. The various iterations of the Eidolon I've heard, while not particularly lush, seemed to be on the warmer, less analytical side. My own take of the speaker (based on limited exposure) is that they needed a touch more liveliness (something from the OTL camp, perhaps, would help).

Still, if you are looking on the warmer side, I would suggest trying the Hovland solid state amp. I heard the Eidolon (diamond) with a Hovland chain of amplification and it sounded pretty warm and sweet.

VAC PHI 70. They have enough power for 95% of the music anyone would want to listen to.

I have tried all these over the last 7 years:
Levinson 333 (sucks allround)
VT200 (metallic, sucks allround)
VT130 (acceptable only with Auricap mod and KT88)
Classic 120 (acceptable only with extensive mods)
Classic 150 (lacks extreme high and extreme low)
VAC Vintage 100 (Triode mode sounds good but may break up / distort when playing piano @ loud volumes)
Canary 309 (no juice)
and the latest Counterpoint NPM with basic Altavista mod.
(great all round, has bass, but not as transparent as Phi 70)
Nothing, absolutely nothing, comes close to the transparency, mid-high dynamic contrast (note mid-high only), and most of all, musicality, of the PHI70s.
BTW dont bother experimenting with tubes, the stock ones are the best tuned for the PHi 70.

"Nothing, absolutely nothing, comes close to the transparency, mid-high dynamic contrast (note mid-high only), and most of all, musicality, of the PHI70s."

I assume this "nothing" includes the CAT amps. And if so, that's quite a claim.

CAT amps... are you referring to JL2?
Not sure if I can even think about go back to listening EL34 or KT88 amps with many tubes on each side anymore.

Well before you come to any conclusion that all multi-tube KT88, 65500 or EL34 amp designs are the same, you should give the CAT amps a listen. The dynamic contrasts and transient speed here is very impressive....and not just through the mids and highs; the amp's performance is unaffected when the performance involves significant low-frequency material. Most tube amps in the 100-200 wpc rating, ARC for example, just crumble during such source material.