My sister recently purchased a pair of Bose SoundTrue headphones for my dad for father's day. Well, I've been testing them out, to see how they compare to my newly purchased Sennheiser Momentums and HD598s. The first time I plugged the SoundTrues into my early-2011 MBP 13", I was turned off by how soft the music was, even at the highest volume. A day or two later, I tried them with my iPhone 5 and I was astounded by how much louder they got, how much richer the sound was. The first conclusion anyone would draw is that there's something wrong with sound card in my MacBook, but that cannot be the case since my MacBook drives my two Sennheiser headphones to higher volumes than my iPhone can. Can anyone make sense of this?