This really shows how personal sound is. I find the DT 1770 and DT 1990 very musical and fun headphones to listen to, especially the DT 1990, I think I must really enjoy the sound, maybe the tactility and power of the sound is what I enjoy, a lot of people actually find the DT 1770/1990 euphoric and musical. I find they manage to be detailed and fun at the same time. The Amiron is more laid-back and relaxed with some of the edges rounded off, it conveys certain emotions better such as sadness and calm and some of the more subtle emotions better, but for more happy, upbeat, aggressive, angry, etc. music, I'd take the DT 1770/1990 anyday as I don't find the Amiron to properly convey those emotions in comparison. I wouldn't really call the Amiron all that fun, rather I would call it soothing.
The DT 1770/1990 and Amiron really don't sound all that alike, they present sound quite differently while you can definitely tell the DT 1770 and DT 1990 are more similarly tuned. I don't find the sound of the Amiron to compete for head-time with the DT 1770 or DT 1990 at all. While my DT 1770 is largely ignored because of the DT 1990.