|Power Rating||Efficiency||90dB SPL||105dB SPL||120dB SPL|
Got bored and did some calculations. Based on this data when you interpolate in an exponential graph you will see that you can get about 110dB SPL at 650mW with the HE-4. If I am interpreting this correctly this means that the minimum power required to get optimal performance out of the HE-4 is 650mW since at an 80dB listening level (Where your ears are most accurate and music sounds the best without too much risk of long term hearing damage.) you get about 30dB of overhead for dynamic range meaning unless you are listening to some insane orchestral stuff you aren't ever going to run into a dynamic range wall.
It's actually around 4mW for 90dB, 126mW for 105dB and 4W for 120dB.
Edit: considering 42 Ohms
Edited by rodweb - 5/24/14 at 10:48am