[hardRocker1423]

     Is it normal for a pair of HE-500 headphones to be able to be powered by an JDS o2 on low volume, low gain, and low volume on the music player? My setup is my computer (vox audio player) to Modi to o2 to HE-500. With the o2 set to about 1/4 of it's volume pot and low gain, unless I turn the VOX player down to 20% volume or so,or the headphones are way too loud. Even at near the lowest possible on the pot, I can still easily hear the music.
 
The reason that I'm asking is that I've always thought that the HE-500s had a low(er) efficiency, and it's always surprised me how easily the small, daily low powered o2 powers it. Is this normal, or is this unusual for these cans?

 

[viralcow]

Well, the whole point of the HE-500 was to make the HE-6 easier to drive. And IMO it runs decently well without any amplification on a phone or mp3 player. So, to answer your question, it's normal.

 

[Head Injury]

       Is it normal for a pair of HE-500 headphones to be able to be powered by an JDS o2 on low volume, low gain, and low volume on the music player? My setup is my computer (vox audio player) to Modi to o2 to HE-500. With the o2 set to about 1/4 of it's volume pot and low gain, unless I turn the VOX player down to 20% volume or so,or the headphones are way too loud. Even at near the lowest possible on the pot, I can still easily hear the music.
 
The reason that I'm asking is that I've always thought that the HE-500s had a low(er) efficiency, and it's always surprised me how easily the small, daily low powered o2 powers it. Is this normal, or is this unusual for these cans?

It's perfectly normal. Headphones, with the exception of the HE-6, are not as hard to drive as people think. The HE-500 only needs about 0.4 V (5 mW) to reach a loud average listening volume of 90 dB. The O2 is capable of 5 V on the default low gain setting with a typical 2 V source. Even the HE-6 would only need about 1 V.