Hmm, so it falls very short in delivering 1 W per channel, man I'm getting a lot of mixed message about the O2 + HE-500. Some are saying the O2 won't power it and it gives poor dynamics and others are saying it works fine and delivers plenty of power. This is pretty frustrating.
See my other post. Lets pretend you have headphone which can do 90 dB @ 1 mW. You have to double the power each time to gain another 3 dBs. By the time you apply a half a watt (500 mWs), you are theoretically hitting 117 dB. You should be in pain at that point, or otherwise unwilling to listen very long. At that point, 1 W is only taking you to 120 dB. 2Ws to 123 dB, and so on.
So, "falling very short of 1 W" is NOT a problem, unless your source is utterly "quiet" or has ridiculously high dynamic range. In that case, you will need a lot of power just to supply the peak bursts of sound that are there.
That said, even listening to Chopin, I don't need more than half a dial to experience the raging crescendos and baby-to-sleep key strokes. Trust me, I sweated the numbers myself. Then I got over it. The O2 provides a ton of power compared to the USB devices, you will have to spend a lot more to get to 1W and beyond.
Edited by MrMateoHead - 11/14/12 at 6:20pm