Generally a good review. All most of us can go on is our own personal experience with a given piece of audio gear, not to mention there's a lot of subjectivity in audio. It's not like video where the differences are immediate when one sees the superiority of one monitor over the other, where better is really better, no questions asked.
My personal experience with the Super 3i goes back to 2010 when the cabinet was an inch narrower and it had the previous hemp cone driver.
I was running the highly touted John Blue JB3 at the time on the desktop. I pulled them and set up the 3i's straight out of the box and played the same music. It was no contest across the board, especially in the bass department with quick articulate transparent bass, unlike the (sometimes, depending on the music) boomy, boxy bass/midbass the JB3s exhibited which sucked the life out of the midrange. I also ran the same Super 3i's with and without subwoofer in room systems with excellent results, albeit with some music sounding a bit thin without the sub. Imaging was insane in all cases. The slight thinness of the Super 3i in some, but not all music was far more acceptable to my ears than the often boomy accentuated bass/midbass many small monitors exhibit. To this day one of the best desktop systems I recall hearing are those same hemp cone 3i's, with a Decware SE84C+, and KingRex UD-01 DAC with external PSU MK2 power supply.
Fast forward to when Louis introduced the RS5 driver in the then new Super 3T (he inexplicably dropped the 3i, and 5 Monitors in favor of the 3T and 3E). In a room system with a Decware SE84CCE Select, the 3T's were sublime - truly the RS5 clobbers the hemp cone. Time for the desktop. Very disappointing with boomy bass/midbass. This new driver with the less stiff surround needed a little more damping than the hemp cone did. The Glow Audio Amp One SEP with it's small amount of negative feedback fixed the problem, as did every solid state amp I tried with these speakers thereafter on the desktop. Where the SE84 or Kitoki (with their zero negative feedback)/Super 3i combo really shine is in a room system, and with the right acoustics and setup, no sub is needed. I find my choice of DAC can have a huge effect on the weight of the presentation.
To say the Super 3i cart blank needs a sub is simply not true. Source, amp, cabling, room acoustics, and the music played have a profound effect on this speaker. In reality, there is no sub on earth that will keep up with it's electrostatic speed, although in some cases a sub can be a help. To this day, after being in audio for over 40 years (with still excellent hearing) the Super 3i is one of the finest small monitors I've heard regardless of price. With a SEP, Class D, or Gain Clone the Super 3i is king of the desktop and to this day I've never felt the need of a sub. With the right acoustics in a room system, I like a good SET (with zero negative feedback) driving the Super 3i.
For about the last almost 50 years the audio industry has been preoccupied with accentuated bass/midbass due at least to three phenomenon: the emergence of rock music with electric bass, cheap high power solid state amplifiers, and more compact speakers with heavier, less efficient drivers. If you are ever privileged to listen to a set of vintage Altecs or the like, you will hear a completely different sound - utterly sublime and "you are there" reality with no accentuated bass/midbass. Sad thing was they were big, pricey, and wouldn't fit in the average home of that day. Simply put, Louis has been able the capture that vintage sound in a much more compact package. I've attended many live performances of different genres of music, amplified and not amplified, and find the sound (including the bass/midbass) that many modern stereo systems produce is not the same - it's artificial.
Addendum:
What would take the RS5 driver to the next level in looks and sound is for it to have a cast basket. 3D imagery has been done for a cast basket and it's gorgeous, almost a miniature of the Alnico basket, but Louis has not proceeded with it. The cast basket with it's much thinner basket frames would allow freer movement of the driver both in and out, generally improving dynamics all around and possibly even efficiency, not to mention the other advantages a cast aluminum basket has over a stamped steel one.
