High Output Preamp for First Watt SIT-3?

Hey Murph,
Thanks for your responses. It is nice to have my energy returned.
Subjective is the word. Since you like how the SIT-3/.7 recreates the lower frequencies and the planar sound, the ultimate solution is getting an Electrostatic Sound Solution rebuilt pair of Quad 57s. This may be the last speaker you ever buy. Especially since you already, lucky, own one of the best amp matches for the Quads there is and, probably, the best First Watt amp made. When I said "sand amp" I was referring to silica or silicon. However, the silicon-carbide-based JFETs in the SIT-3 may be the best application ever of a sand amp. This amp creates a midrange to die for with very little SS glare and a solid bass. And 57s create a midrange that is, to this day, the industry standard. Many, many speaker designers use them as a gauge to guide their developments. 
Regarding your MoFi MM cartridge, it seems to be a very good one. I don't think the 3mv output is an issue. Industry standard loading for MM phono stages is 47ohms which is appropriate for almost all MM cartridges.
I raved about the Audible Illusions M3A/B. That stands. Though still a SET guy, I think a good SS amp and good tube preamp is a great combination. You already have a great, maybe even classic amp. Why not go for a great and classic preamp like the Audible Illusions M3A/B with an excellent SET phono stage?
As said, you fortunately own about the best SS amp ever designed. Cherish it.
If you want to have a second system or alternate speakers my only suggestion is to go with a little known Canadian company-Tetra Speakers. I own their $16K Phoenix TZs and their $1500 entry level 120Us. Tetra's designer, Adrian Butts, is very much like a great musical artist in his ability to capture the "rightness" in a speaker unlike any speaker brand I have ever experienced. This is clearly reflected in the many great musical artist using and endorsing his speakers. From Keith Richards to Herbie Hancock, they all make similar comments. When going to Tetraspeakers.com, the first image you see is Keith Richards who says: "They're not just ANY pair of speakers"! If I sound like I am selling Tetra speakers, I am. I want to turn all friends on to Adrian's work. I have been at this quest for the "right sound" since I was 18. And a professional in the Audio Industry for almost 40 years. I have never heard a speaker company who is able to consistently capture the essential soul of the music anywhere close to Tetras.
Adrian sells direct so, even though I put on my salesman hat, I make no money for my recommendation. Owning his entry level 120Us made me just one of the many musicians who own and adore Tetras regardless of the level. All Tetras have the house sound just increase in their output.
I do long for Quad 57s and am clear about my recommendation. But my Tetras make me not anxious to get another pair or Quads. As much as I love the Quads, I love my Tetras more. There is no other Audio Industry company of any kind who have this kind of amazing and terrific endorsements. The Tetra speaker website is one-of-a-kind and a convincing testament. Check it out. BTW-I use a SET 300B amp to run my Tetra Phoenix TZs. Not the last word in Rock but, like you, I am very happy with the match even though my First Watt M3 gives me more bass and a fuller sound, I adore the "magic" of the SET. All Tetras work well with 8 watts of 300B. 

Look at the Tetraspeakers.com site and any other Audio Industry.
I have known some top level Grammy winning artists. They normally do not involve themselves with any commercial enterprises unless they art financially invested (with the occasional exception of instruments from large companies). Tetra sells retail to all endorsing artists except Keith Richards for whom Adrian made a custom pair of Tetras for him to take on the road.

Hi Murph,
I have pretty carefully read your posts. I relate to your perspective on music playback. Until recently I was a working musician and have made a living as an audio consultant and dealer. I own one of Nelson Pass’s “kitchen table” creations, the M3. Believe the SIT-3 is one of his better works. And there are two main issues, as you mentioned. Speaker and amp combination are the “two hands clapping” in any system. And the preamp is “the heart”. Central is your feeling of how the music sounds. If you like the Maggies you are not going to get that open sound from any other speaker that works for you other than a legendary pair of Quad 57s. It is counter intuitive, but if the SIT-3 and the .7s work for you they work. But the First Watt should be an excellent match with the 57s. I would save your money and stay with what you have. BTW you have one of the best TTs for $2k out there in the MoFi. And the your digital is said to be terrific although I am not a digital guy. An excellent phono stage and, according to TAS Editor’s Choice for many, many years as “the best at any price”, is the Audible Illusions preamp. The model with the phono stage is the M3A or M3B. I own and adore my M3B. A new one is $5200. But you can get 90% there with a factory refurbished one for around $2500. One of the fortes of the AI is that they are a SET design using only one tube per channel for the preamp and for the phono stage. And a SS amp is normally smoothed off by a tube preamp-let alone a SET. I know Dan Wright very well. I did an audio show with him. You can’t go wrong with one of his preamps but I prefer the AI. Unfortunately, a SET amp is a bridge too far for the Maggies. I am an all SET guy for life. Unmatched musicality with the right speakers. As good as the First Watt is, it is still a “sand amp” and has a SS sound.
But if all those wonderful reviewers and YOU love this combo, stick with it. Some day, or now, you may want to get Quad 57s. I joyfully lived with my 57s for 10 years and still miss them. But something you don’t get with 57s or .7s is dynamics and slam. This can be helped by adding a subwoofer. I would only use a Rel. They only make subs and they hook up directly to your amp making for the best connection. Surely, you may be more able to better push the Maggies with a higher power amp but adding an AI will give you substantially more gain and adjustable gain for MM. Matching amp with speaker is about the toughest thing in a system and if you, mostly, like what you have, be happy! Some day, you may want to get a SET. Ultimately, there is nothing that compares. SS amps try to sound more like tube amps and multi tube amps are trying to sound more like SETs... mostly.