Founded in 1972, PSB Speaker is a niche but high-end speaker headphone brand. It is loved by enthusiasts because of its excellent ability to reproduce the true frequency curve. In the U.S. Consumer Reports, the PSB Speaker M4U 4 scored 86 points, tied for second place. Although the M4U 4 is on the expensive side at around $290, if you're a headphone enthusiast, you'll find it worth the price. The M4U4 is an in-ear headphone that you won't feel its presence even if you wear it for a long time. Its performance in terms of sound quality is rated as excellent, and Consumer Reports also gives it a high rating: "While there is no perfect headset in the world, the shortcomings of the M4U 4 are really not worth mentioning. "In the face of such excellent and niche headphones, the biggest regret of domestic consumers is that they are not easy to buy and need to be shopped overseas.