@jeff1225 Thanks for your kind words. In my system, I prefer the F2/J to the SIT-3. That may seem unusual considering the vaunted reputation of the SIT-3, but one must keep in mind that the F2/J's unique topology was literally designed for single driver, crossover-less speakers like mine. I won't go into the details here, but if you've read up on the F2/J's design, it's really unique and has huge advantages when paired with single driver speakers. In my system, it sounds expansive, relaxed and "boosted" in the highs and lows, the latter due to the way its unique design ignores the impedance curves of my speakers.
The SIT-3, on the other hand, seems finicky about what speakers (and loads) it plays well with. I think it likes very linear, 4ohm loads; my speakers probably have some impedance swings it doesn't like. It sounds just a little restricted in my system - but very vivid, and lit-from-within. It's a fine amp, but synergy is super important, and in that aspect the F2/J wins out.
I do have a Don Sachs Model 2 preamp on the way, so I'll give that a try and see if it doesn't get more out of the low-gain SIT-3 than my LTA MZ2 does.