One well-known and fine attribute about the 1plus2 is its bass. I do not believe I have heard bass in an IEM that was so exciting, powerful, yet high quality in the 1plus2. The Ref. 1 takes it to the next level, without a doubt. The bass is seriously awe-inspiring. In my opinion, it does a better job than many full-size cans, and sort of defies explanation. It is wonderfully textured and of very high quality, no doubt. But at the same time the sub-bass is powerful, digs deep into your ribs, and rumbles - the mid-bass POPS with serious impact. It has the characteristics of a well-done mid-bass centric can, and the characteristics of a quality sub-bass centric can. Not that the FR is bass-centric, just using those examples.
The bass is palpable and textured. It bites, rumbles and is of very high quality. The reverb and decay are natural sounding, the upright bass so realistic up on that stage for the jazz trio. Bass so natural and life-like, huge for this earphone.
Seriously this bass is something else. It's not something else for an IEM, it's something else, period. So rich, so clean, so enjoyable. From jazz to EDM, a pure joy. How do you improve on the bass response of the 1plus2? You invent the Ref. 1. I like to give reserved impressions, and let the reader determine if what I'm writing works for them. But the bass is so impressive on these things that it makes the 1plus2 sound considerably more flat. But everything is so highly refined on the Ref. 1, with that sweet high-end, there is no lazy bloom evident. The bass is nimble, the bass is spectacular.
