I've just had the X3 for a few days, but I noticed a big improvement going to high gain vs low gain. Low gain had more compressed dynamics, more grain in the treble. For example, Art Gafunkel's voice with low gain sounded like rayon, high gain sounded like silk on a 16/44 flac of What a Wonderful World. The air around high voices improved with high gain. Low voices like my 24/96 of Strange Days with Jim Morrison's voice not as affected. I'm using 3.2 firmware, using old Grado SR225e and Ultrasone DJ1 headphones just out of the box. Both phones are 32 Ohm, not particularly hard to drive with very different sound signatures, but both were equally affected by the change. Even though I have to put the volume at less that half, I'm sticking with high gain. Low gain makes mine almost as bad as an iPod. I'm glad I found that switch!