Ive listened to the Ultrasone HFI-780, Sony MDR-V6 (MDR-7506), Grado SR80i, and the Sennheiser HD598. The HD598 wins. The Ultrasone HFI-780 has absolutely terrible sibilance/sibilant. This is a common complaint with these cans. The 780 has better bass than the HD598, but the sibilance ruins these cans. The Sony MDR-V6 (aka MDR-7506) are phenomenal cans, but rather boring. These are some of the most popular headphones ever made, for good reason. They do sound incredible, and they are inexpensive. Every sound is fantastic. However, its boring...

This is my fist headphone amp, so I don't have anything to compare it to. I have the Sennheiser HD598 headphones and my first generation Microsoft Zune had a tough time giving them enough power. The CMoyBB makes a huge difference! I can now listen to music as loud, and louder, than I want to. The CMoyBB could easily blow my headphones if I wanted to, that's how powerful it is. There is no background noise, such as hissing or static, from the CMoyBB whatsoever. The bass boost adds the perfect amount of bass, which the HD598 is notorious for not...