My brother owns the 20.1 driven by top of the line Audio Research amps, preamps, etc. It sounds amazing. SOTA in dynamics, accurate powerful bass, speed, transparency, etc. However, for my room, preferred budget and my listening preferences, I actually prefer the 3.7, and just bought a pair. The 3.7s are the only Magnepans I've heard that keep all the Maggie traits I love (speed, transparency, dynamics, scale, immediacy, etc.) but also solve some of the traits that kept me from buying any of the Maggies for my system. The 3.7s strike me as being the most balanced from top to bottom (e.g., when I heard 1.7s and even my brother's 20.1s it seemed the center of gravity was in the treble region, whereas 3.7s don't sound tipped up or aggressive in the upper regions....TO MY EARS). The 3.7s also keep a large sound stage but put the performers and instruments to a more reasonable scale (no more 20 foot tall singers or 12 foot saxaphones). In addition, the 3.7s are the first Maggies I've heard where low level listening didn't come across as less than stellar. The 20.1s are amazing, and I can't imagine what the next version of those will sound like, but for my ears, I voted with my wallet for the 3.7s...and I could have splurged and bought the 20.1s. I think to get the most of the 20.1s one needs massive amplification and a very good sized room.