# Can an aune b1 power a hifiman he4xx at 80 - 90db properly?

I tried figuring it out myself but couldn’t get it lol. Guess I should go back to physics class…

It seems neither HiFiMan nor Drop are professional enough to quote the sensitivity properly in dB/V or dB/mW, but from practical experience it’s safe to assume their incomplete spec of “93 dB” is in dB/V (rather than dB/mW).

Now since we know how much they put out per 1 volt, we need the amp’s max output in volts over this 35 ohm load and we can do 93+20*lg(Uamp/1V) to get the decibels.

Spec says the B1 can do about 500 mW into 35 ohms, so Uamp^2/35 = 0.5 W, Uamp^2 = 0.5*35, Uamp = sqrt(17.5) = 4.183 V.

So max power from the B1 into the 4XX = 93 + 20*lg(4.183) = 105.4 dB.

The other way to do it is first convert dB/V into dB/mW, then see what that comes to at 500 mW.

Power @ 1V = 1^2/35 = 1/35 = 28.6 mW.
Decibels @ 1mW = 93 + 10`*`lg(1/28.6) = 78.4 dB
Decibels @ 500mW = 78.4 + 10`*`lg(500/1) = 105.4 dB

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Ty soooo much 