In this video I tested the ROSESELSA x AAV CJ20, a $169 single planar IEM that’s slightly open, and I broke it down the same way I always do: build, sound, graphs, and where it lands in my rankings. Build-wise, it’s a slick, unique-looking gray metal shell with a solid fit and good isolation for being a little open. It’s 2-pin, the nozzle holds tips well, and comfort was a non-issue for me. Accessories are decent (tips, cloth, brush, pouch), and the included fabric cable looks good and has a working chin slider—but I’m personally not a big fabric cable guy, so I didn’t use it much. Sound is where the CJ20 gets interesting. It’s a planar, but it’s tuned with more “ump,” swagger, and fun than a lot of the typical safe planars. The sub-bass is authoritative with great rumble and texture, it’s fast, punchy, and stays clean without mid-bass bloat. The catch is the upper mids: on the right tracks (rock/metal, alternative stuff like Green Day) it’s vibrant and engaging, but on other music—especially delicate vocals or some pop like Michael Jackson—it can get shouty and not as natural. My takeaway: it’s a great specialist set, not an all-arounder, and it’ll shine hardest if your library matches what it’s tuned for (or if you’re willing to EQ that upper-mid peak).