Tube amp for Avalon Eidolon ?

John, you're on the right track to consider using tubes with the Eidolons. People who have heard the Eidolons only with solid state amplifiers simply have not experienced what this speaker can truly deliver in terms of pure musicial enjoyment.

I use Atma-Sphere MA-2 MkII.2s with my Eidolons. I think this match is incredibly good. Regular Audiogon contributors Slipknot1 and Trelja have listened to this combination at my house and can offer their comments.

For me, the Atma-Sphere MA-2s have the quickness, neutrality, dynamics and bass definition to complement the Eidolons extremely well; musical "authority" is definitely present. Resolution is very high, including at low volume levels. And the Atma-Spheres deliver a natural musicality, with very accurate rendering of timbre and harmonic overtones, that makes listening to acoustic music a joy.

Other Eidolon owners have reported good success with some other large tube amps, but these big Atma-Sphere all-triode Class-A OTLs make the magic for me.

Used MA-2s fall within your stated price range, and if you ship them to the factory, Atma-Sphere will check them out, bring them to current production spec (if needed) and re-up the five-year warranty to you as the new owner for a reasonable fee.

http://www.atma-sphere.com/products/ma2.html

You can get some sense of my listening priorities, and see how they may match to yours, in the postscript to my review of the Walker Proscenium turntable.
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Along with Rushton's recommendation, I'd strongly recommend CAT.

Brian

The other day I helped a friend install a pair of the Tenor 300wpc amps mated to the Avalon Eidolon Diamons.

Not only were the amps beautiful in cherry wood, but within only a few minutes they really began to open up and produce a nice full and warm sound along with a fairly resolving high end.

New these would be out of your alotted budget, but Tenor does have other models.

-IMO

VTL M450 or higher.

Rushton is spot on. I have had the pleasure of repeated listening sessions at his home. Anyone who says that tubes can't do bass have never heard the incredible synergy that exists in the Eidolon/Atma-sphere MA-2 pairing. This pairing presents a believable, palpable soundstage that extends way behind and to the sides of the Eidolons to the point where they disappear and all there is is the music. Resolving of detail and nueance at any volume level (a major plus if you are like me and don't listen at crushing levels), but also capable of natural unstrained high volumes. Rushton's system is one of the most truely musical non-fatigue inducing setups I have ever heard (of course it does not hurt that his source, preamp, and cabling are top notch as well). That said, I have heard many mega-buck setups that don't sound as believable as his does. He has paid attention to the details of setup, power, cabling and that all-important synergy of equipment combination.
If you are considering the kind of investment this pairing involves, you would be doing yourself a huge favor by paying attention to Rushton's comments and perhaps reviewing some of the other threads he has contributed to.