Is the Manley Steelhead still relevant?

@drbond 
Depends on your budget.
The reason I suggested the Atmasphere MP1 or MP3 is they are certain to have enough drive to match the the MA1's. I think you can get these with or without a phono included in the preamp.
The Conrad Johnson ET7 up to the Gatt have very good drive for insensitive amplifiers. A friend of mine has recently purchased the Conrad Johnson Gatt2 - it is stunning but of course it has a big price tag. It's a forever purchase.
Air Tight are also very good - the ATC2 has great drive and can be obtained at reasonable prices second hand due to being less well known.
Audio Research in general I find a little brash for my taste and I think the others offer better value.

How much do you want to spend ?

@dover 

My budget for a pre-amplifier could be $30k, if it was exceptionally better than one that could be obtained at $20k.  So, essentially, I don't want to spend $100k+, but it seems that many highly esteemed pre-amplifiers are selling for $10k-40k, which I suppose could be a reasonable range.  

I am not partial to any particular brand either:  perhaps the Atma-Sphere pre-amplifiers would suit all amplifiers the best due to its transparency, although maybe a Lamm pre-amplifier would be better suited for the M2.2 amplifiers.  Or perhaps there's another lesser known pre-amplifier that would suffice?

(I have Sound Lab speakers, and listen to purely classical and chamber music.)

Thanks.

If you have SL speakers driven by Atma-sphere amplifier s, I strongly recommend a balanced phono linestage. Of course the Atma MP1 would be logical. The atmosphere amplifiers really do come alive when driven in balanced mode. I would not spend big money on a single ended phono line stage to drive balanced amplifiers.

@lewm

Thanks for the pointer. That restriction would exclude the CJ line, so A-S and Lamm could still be options, as well as other balanced (XLR-based) pre-amplifiers.  Ideally, I suppose the pre-amplifier would include both XLR and RCA output lines. 

To my knowledge, Lamm does not and has never made a true balanced preamplifier, either phono or line stage. But I am not a Lamm aficionado, so I may be wrong. You do have to be careful when you shop for balanced equipment. Many manufacturers will let you believe that because their equipment has an XLR output jack, it is balanced inside. That is often not the case. Or some use an added active circuit or transformer at the “balanced” outputs, to generate a balanced signal from a single-ended circuit.That ploy works in terms of a balanced output, but it generally adds coloration, and in such devices the single ended outputs often sound better than the balanced outputs. Keep in mind that I am not saying that balanced always sounds better than single ended, although I do prefer wiring cartridges for balanced drive into a balanced phono stage. I am only saying that atmasphere amplifiers sound best by far when driven in balanced mode. It is well worth the effort. Moreover, driving the amplifier with a balanced preamplifier mitigates its relatively low input sensitivity, by 6db. I have been using atmosphere amplifiers for 25 years, and I have experience listening to them when driven both single ended and balanced. Once I heard them driven in balanced mode (by my MP1), I never looked back.