Mike, you haven't mentioned Pass in your line-up of amps. Are you not considering them or have you listened and haven't been impressed. By not impressed I mean with how they work with the speakers you've been auditioning, not a general overall statement.
Doug - that's a great question. My audition of the D'Agostino monos reminded me of some of the fine qualities of Pass amps - liquidity, smooth top end, and just this incredible "flow" to the music. The D'Agostino amps had slightly better over bass control and slam than my Pass amps, and may have been even a little sweeter on top....but the Pass trumps them in midrange bloom and presentation.
Given that one amp is $55,000 and the other in the $20,000 range - the Pass is definitely the better value. Oh, and both get hot as hell....so there is no winner in that category.
Now, as for Pass for Raidho, I cannot emphasize enough the "out of box" thinking these speakers require. Prior to purchasing my little Raidho D1's, I did a lot of research and spoke to a lot of very knowledgable people (Jon - VT Skier being one of them). Jon has heard more speakers in the past two years than anyone I know. He has been extremely helpful. I also emailed and spoke with Lars from Raidho. John from Audio Salon was also very helpful. Angie at Angie's audio too. I then read everything I could on the Raidho C and D series.
Some of the things I was told, I didn't understand or didn't want to believe. Things like "get control of the bass, and the rest will take care of itself" or "tubes and Raidho don't mix".
It wasn't until I got my D1's home, setup, tried them in two different rooms, in various setup positions and with my ARC REF 250's, ARC DS 450 M's and Classe CAM600's, that I fully understood what people meant.
We are so used to an amp having a profound impact on high's and mid's and bass. But with the Raidho's, the mids and highs sounded almost the same - regardless of which amp I used on them (and preamp). They have a dominant tweeter (in the dominant/recessive gene sense). But that tweeters dominance is something you want. Trust me! However, what affected their sound the most - was the amp with the best bass control. There were only subtle differences in the midrange/highs with the various amps. But there was substantial differences in bass control, slam and the depths to which bass notes plumbed when I worked through the various amps.
Trust me - I'm not considering Soulution because it represents any great "value" or some great watts-per-channel calculation. LMAO! But, I have heard Soulution amps and loved what they did in the bass department. Iron fisted grip. Seemingly going lower. Better bass definition. But truthfully, it wasn't until Cyril provided me with the dampening factor (thank you Cyril) - that what I heard now made sense.
So, to answer your question, I love Pass amps and for 99.999999% of the speakers out there, they are excellent. I'm just not sure how they would sound on Raidho speakers. They might be excellent. Jeff Rowland 725 amps don't have a particularly high dampening factor, but they are always used to demo Raidho speakers. Same for D'Agostino monos (my audition on Wednesday is still haunting me.) I've heard no other amp which can invoke such emotion. Let me tell you, my head is fighting my heart (Soulution vs D'Agostino).
I would just like to add that everyone - everyone - needs to get out and listen. What I may like, you may not and visa-versa. There is no "one size fits all" in audio. My friends from the local audiophile club tell me to this day, "Michael, the best system you've ever owned is the Strad/Pass setup".
I feel that of late, I have let my guard down. I used to always go and listen before buying. But, I became complacent. Lazy. Trusting reviews. Trusting others - when I should only trust myself. My trip to Phoenix in May, my week long listening ventures in Toronto a few weeks back, my trip to Miami and my upcoming trip to RMAF are all overdue listening sessions to formulate new reference points. I realize that multiple listening sessions, in different rooms, with difference gear is ultimately needed to form conclusions one way or another - but I at least now have a much better understanding of some of the latest gear: Strumento, Vitus, Soulution, D'Agostino, Accuphase, Levinson, Constellation, MBL, Focal, Raidho, Wilson, Burmester, DCS, Linn, Boulder, Magico, Vandersteen, Joseph Audio, Vienna Acoustics, Basis, Ayre, Esoteric and countless others are now all in the memory banks as reference points for what I like, and more importantly, what I didn't care for.
I've learned of late, things I thought I would like - I didn't. And things I didn't think I would care for, I loved.
Let me leave you with this last thought.
It's not what reviewers say that's important, it's what they don't say.