I previously owned the UM2 for more than 3 years and had a lot of fun with it until i gave it away last year. I heard a lot about the SM3 but i never expect it to be this good. The bass, detail and soundstage surpasses the UM2 in almost every way. The bass is as much or even more than the UM2 but much faster and more controlled, smooth mids and almost no hiss. The soundstage is huge and amazing. Seriously I´d take these over everything i currently own when it comes to music listening including my Razer Mako, K701 + Heed Canamp + V-Dac.   +...