I've had my HD 650's for a while now and I've paired them with a Modi DAC and Qinpu A-3 amplifier. I've read lots of posts about recommendations for amps for high impedance headphones and am confused about how loud these headphones should sound with and without an amp. In terms of clarity, there is a significant improvement in sound quality when I switch from just plugging in my phones directly to my MBP to my current setup, but both systems are loud enough for listening even when not at maximum volume. I even plugged them into my smartphone and the volume can be still raised loud enough to hurt my ears. Why doesn't it sound too soft or quiet like I would anticipate from reading other forums even without proper audio setup?