First Watt SIT-3 proper speaker matches

I'd think any of the SET tube guys speakers would be up your ally. I've tried and liked the above mentioned Omega SAM's, I own and love the Living Voice Avatar 2's (look further up the chain if your budget allows wonderfully musical speakers, also note UK pound makes these a much better buy right now), Tekton, Zu audio and Horns are a few others from the top of my head. Try searching high efficiency speakers here, there are quite a few good threads. 
I run a SET 8wpc amp so I'm familiar with your issue and its not backwards you just need to focus on higher efficiency speakers above 94db, depending on your listening volumes maybe 98db if you like it really loud. 

As I recall from a recent review of the First Watt SIT-3, they work well with speakers that are 4 ohm and have 88dB sensitivity. In the review, the reviewer raved about how the Magnepan .7i pair sounded. However, they have a 86dB sensitivity. I have an SIT-3 (as a second amp) and Maggy 1.7i pair which also are 4 ohm and 86 dB. They sound great. Of course the volume knob on my preamp turns more to the right to move up the volume compared to my more powerful amps. So I am due to take delivery of my new second pair of speakers, the Magico A3. They are rated at 4 ohms and 88 dB. So I’ll see how they sound.  

I am very interested in this discussion. So, if the Spatial Audio M3 TriodeMasters are 12 ohms and 93 dB, that would not be a good match for a First Watt SIT-3, right?

I don’t want to hijack this thread, but that makes me wonder which First Watt would match the TriodeMasters well. I know they’re designed for tubes, but I’d like to try a lessor powered solid state amp with them. 

my answer is probably backwards, but I currently have an F7 driving a pair of Rethm Maarga and it is doing a wonderful job.  The retime are a wonderful sounding horn with built in powered bass.  I am awaiting my SIT-3 which I suspect will also drive my Rethm beautifully.  And I am planning on trading out the Maarga for Saadhana at the end of the year.  They are 100 dB efficiency so fairly easy to drive.  I would seriously consider auditioning a pair of Rethm before you make any final decision. not a dealer, just a big fan.