I have a question about my phones audio and the headphone jack. First of all is it same to use the device on any headphones OR line level amp? Is the on-board amp capable of matching any impedance or can using/swapping different output sources damage the chip? I ask because I often use the headphone out to play on my stereo system or portable speakers and have noticed that it takes nearly full volume to reach what I'd consider " line level ". Some receivers; like a home theater, my phone outputs very low and takes a lot from the amplifier to get loud. Any kind of high fi audio receiver is like this while cheap things; I.e computer speakers it has plenty of power. When hooked to headphones full volume is barely enough to be loud but different types of phones work differently. Small ear buds work best but even then don't get very loud and large earphones are either inaudible or just barely loud.