I tried (with my Coincident Super E's) the Manley Retro 300B's--in some weird, interim version (circa January 2000), the Manley Reference 250's, Atma-Sphere M-60 and MA-1's, Cary SLAM-100's, Cary 805-C's, and the 47-Labs Gaincard-S (50-watt version, with double power supplies).
If I were to do it all over again, I would go with Atma-Spere gear (pre-amp and either the M-60's or MA-1's if you have a large room and deep pockets). When you get the A-S/Coincident combo working right (and that takes some doing), I would be surprised if you were not stunned by the life-like qualities this combo can produce. Provisos: Only go with a balanced (XLR) setup where ever possible and definitely only balanced between the pre-amp and the mono blocks; Only use US NOS 6SN7 tubes in the amps, and Svetlana power 6AS7 power tubes; Pay special attention to the cabling (Nordost is what Paul Bolin [TAS] recommended to me--I have good success with Coincident IC's), and make sure you can isolate the A-S power amps well.
At the time I made my amp choice, I opted for the Cary SLAM-100's because the A-S MA-1's were too expensive and would involve too many other system changes, but let me tell you...I heard potential in that A-S/Coincident combo that made me drool--and that's a good thing. The Cary 805-C's sounded slow and congealed to my hear, the Manley Retros were probably "off" (as the cream being 'off') in some way because they just did not sound right in my system or in a friend of mine's system. Mind you, the Retros have gone through some version changes of the last 4 years; I must have had some strange proto-type that did not last long as a model revision. The Manley 250's had incredible bass, but they too sounded as if they were tripping over themselves (timing was off). Perhaps both Manley amps simply did not like working with my pre-amp at the time (Cary SLP-98p). The Manley amps may very well have been so good that they out classed the rest of my system, and I could not tell what was really at fault. I double-checked both amps in better systems.... Who knows?
If you listen to demanding music (large orchestral or heavy-duty pop) in a large room, the Cary SLAM-100's (95 triode, push/pull watts) have a fabulous balance of detail, guts, and musicality. They too benefit from good tubes.
As a side note, I personally think that many folks over look the Super Eclipse glories on bigger tube amps. The Cary SLAM-100 can play delicate passages well AND give you the sense of weight and air being moved by music reproduction that is quite a bit reminiscent of a live orchestra really going at it. Deep, deep, tuneful bass, etc. The obvious area in which the A-S MA-1's just beat the pants off of most amps and ALL Cary amps I've ever heard is the upper frequencies. A-S amps simple sail higher more quickly more accurately than any thing I've heard. A-S amps make most other amps sound positively truncated on the top 6th of the musical spectrum IHO.
As for price, the SLAM's have been discontinued; they probably can be picked up pretty cheaply. The Cary SLI-80 and V-12 amps have been successfully mated to the Supers. They're all cheaper than the SLAM's. IMO, SET's are overrated, even on the easy-to-drive loads of Coincident speakers. Perhaps I just haven't heard a real-world SET done right yet.
Good luck
