Mike, the Raidho D3's sound like amazing speakers. You mentioned some very good amps. I own a pair of Magico S5's and have heard the S5's with Vitus & Soulution amps. I liked the Soulution 710 which sounded very smooth and relaxed, much like the S5's. As for Vitus, i've only heard the S5's with the Vitus RI-100 integrated and liked the tonal balance, but overall preferred my Boulder amps which subjectively sound more powerful & transparent. If you were going for Vitus, I would recommend their mono's which achieve more acceptable channel separation. I've heard various Rowland amps, including the 725 mono's. I don't know, when I hear them I hear some artifice which I find a bit fatiguing in long listening sessions. Maybe that's due to the op amps or switcher psu? The weak point of Rowland imho is their preamp. Spectral i'm not a fan of. They sound too clinical and bright for my liking. You correctly pointed out the Raidho's diamond drivers & ribbon tweeter require plenty of clean power which can match them for speed. I don't have access to D'Agostino or Constellation gear; both could be good options. If you're still auditioning amps later in the year, i'd include the new Boulder 2160 which should be excellent. Boulder have also just released the new 2110 preamp which from all i've read is outstanding. Enjoy the process.
