Best amp for Avalon Eidolon speakers?

The Avalon Diamonds were driven at CES by Tenor or Lamm. Sound there and with Kharma Midi and Rockport were the rooms that stood out. All three were using Tenor or Lamm and all with Audio Aero CD players driving the amps direct, if I remember correctly.

Try to demo the Tenors and Lamm's, along with the Atmasphere's already suggested here. I think it worth a shot to listen to the Wolcotts ( properly tubed out ). These provide amazing results on my Soundlabs. The Wolcott would be a relief for your budget after having just purchased Avalon's. At least half retail the others, and a third the price of the big Atmasphere.

The Atma-Sphere MA-2's are a good match with the Eidolon's here. Excellent control, extremely quick, with beautifully natural timbre and harmonic overtones on acoustic music.

I second the Spectrals if you're interested in fast solid state. Very musical, great staging, uncolored, and beautifully detailed. The monoblocks need a Spectral preamp and MIT cables, however Spectral makes an amp that can be used with any other components (DMA-150S) and reputedly has much of the capability of the monoblocks.

I too have heard the Avalons with Spectral and a Wadia source and was struck by the soundstage, transients and very natural decay - all in a super well treated room.

I have a budget(?) Avalon Radian setup that I just put
together with all Spectral electronics (all from Audiogon).
Yes the DMA-360 monos are glorious but they are around
$9000 used if you can find them. A nice alternative is the
DMA-200, which is a pure Class A amp which idles at 800 watts, the ONLY down side is the fan of the older units
run loud, so replacing it would be a good idea. It will definitely power the Eidolons. Preamp: the DMC-30, DMC-30S,
or the DMC-30SL are excellent, in particular, the DMC-30SL;
it throws the largest soundstage, highest resolution, and superlow level resolution of any preamp I have heard. The downside is you need an outstanding DAC/processor or else the DMC-30 series will show off the faults of it(very easily heard). A Wadia 850 is a very good choice for under $3000. Also, the upside of the DMA-200 is that you do not necessarily need MIT cables, the DMA-360s do. . BTW, room acoustics, and speaker placement make or break most Avalon speakers, not electronics. They will either sing like a bird or howl like a dog if the room and speaker placement are not optimized. Also, if you want tubes, Albert Porter's suggestions hit the target dead on. Good Luck