Goldmund, Accuphase, Rowland--any of these three brands are so musical sounding, best solid state. I have heard all three mentioned favorably on Avalons by owners. Surprisingly, the amps Avalon seems to prefer--Spectral--these I have heard on Eidolons and didn't like it at all. Having owned Rowland amps before, I can confidently recommend them as worth your consideration though. A current MC-6 or now-discontinued 8Ti would have MORE than enough juice to manhandle the Eidolons.
PS--from first poster, I too have heard new Millenium amps from Goldmund are a significant improvement over prior Mimesis version amps. Haven't had the pleasure of hearing them myself though.