Well, consider that when the 1.7 came out in 2010, it was such an improvement in coherence, low-level resolution, power usage, etc., that it sounded fundamentally better (and was easier to set up and use) than the rest of the product line.
Magnepan then upgraded their entire product line: Soon the 3.7 replaced the 3.6, the 20.7 replaced the 20.1, and they introduced a new entry-level model, the .7.
The *.7i product line has evidently reduced the Magnepan caveats
such as extreme appetite for current/power, and lack of coherence. I have been living with my 1.7s for four solid years, and I am amazed and drawn into the music every time I play them.
For electronics I use handwired PTP tube preamps (phono and line) from MAGI, feeding a 1980s Perreaux PMF1150B MOSFET power amp.
I also use a pair of small powered subwoofers. Good subs can significantly expand the Maggies' dynamic range and room-filling capabilities. Your SVS Ultra sb-13 should work just fine.
