I won’t be able to give comprehensive answers to all of your questions in one go, and some will, as you suspect, have to wait for a final review, but I’ll hit the highlights:
I can’t imagine you’ll ever get consensus as to which amplifier is best - it’s going to vary for everyone based on, at a minimum, other aspects of their system and their personal tastes. I can rank those mentioned, and a few others, in descending order of my preference (best first), though.
- Linn AK2200 <=> Chord Étude
- Anthem STR
- AHB2 <=> 2x Vidars (monoblock mode, requires differential input)
- 2x Aegir (monoblock, requires differential input)
- Ragnarok 2
- Vidar (Stereo)
- MA252
The Linn/Chord units sound more similar than not, surprisingly. I’d choose based on brand, form-factor and price/availability factors. I went for Étude primarily for form-factor reasons/it fitting in my Chord stack more cleanly (my speaker system is all Linn).
The Anthem is great, but bigger, heavier, more expensive, and no better than the above units.
The AHB2 is a bit on the lean side for my tastes, but it is very resolving. The dual Vidars get close on resolution and have a fuller sound, with better bass presence, for half the price, but need more space. Personally I’d likely go for the dual Vidars of the two here.
Dual Aegir’s (fun to track down at the time) were very good (though one definitely isn’t sufficient). It’s a different presentation to the Vidar, and I think the low-end suffers a bit, though the mids are, perhaps, preferable with the dual-Aegirs. Listening level might sway things here, too.
Ragnarok 2 (didn’t get much time here) has unusually good synergy with the SR1a. Despite being less powerful than a single Vidar, it just seems to mate well with the RAALs.
However, the single Vidar has the edge on grunt here.
The MA252, while a nice piece in general, doesn’t do it for me with the SR1a. It was indicating clipping at lower levels than I wanted if I had my bass-lift EQ in place (and it was needed here). It was also not as resolving as I would expect at the price … and if you’re not going to exploit the SR1a’s resolution and speed, there are other ways to go, headphone wise, that don’t need speaker-level amps.
I’m trying to land a refreshed Linn Klout as an off-the-wall option (they were fantastic with speakers), hard to track down, and will need new caps, but it’s a marvelous bit of kit (assuming my nostalgia isn’t clouding my recollection).
Other amps still on the list … though.
Depends on your music and listening level, but the power requirements don’t really change for a pure class-A amplifier vs. anything else. 100w into 8Ω or 150w into 4Ω.
I wonder if you’re confusing class AB amps and how far they are biased into class A operation?
Definitely not a non-starter. But a sufficiently good one, at the necessary power rating, will not be cheap (nor cool-running or small, and may well need fans … unless it’s built like the original, big, Krells).
Depends on your source and how it handles variable level output.
With a Linn K/SDM or Chord DAVE, the built-in volume-control/pre-amp functionality was preferable to me than the most transparent pre-amp I’ve used (Linn Klimax Kontrol - not longer made), and quite noticeably better than, say, through the pre-amp in my Phonitor X. The RME ADI-2 DAC fs has a sufficiently transparent built-in volume control too.
If you do it in the purely digital domain, sure. You can use EQ up to the same standards as used in original creating the music. It does mean having a computer in the chain somewhere.
Otherwise you have to either handle EQ in the analog domain, which has a certain purity to it, but tends to be in unnecessarily wide bands and isn’t very precise, or go through an ADC somewhere - which I would NOT want to do.
At a very high level … read this.
I’m back listening to the SR1a today, since the MySphere demo set is on it’s way back to Heinz. As good as the MySphere is (and they truly are excellent), the SR1a was immediately impressive all over again.