Quote:
Wouldn't that translate to a huge amount of loudness on my 32ohm cans?
No, because the output impedance attenuates the voltage on a lower impedance load more.
Here is how the power output from
V voltage into
Rload through
Rout output resistance can be calculated, assuming that no current limiting occurs:
P = (V * Rload / (Rload + Rout)) ^ 2 / Rload
With V = 7, Rout = 10 (approximate values for the Xonar STX), and Rload = 32 or 600, the power is:
32 Ω: 889 mW
600 Ω: 79 mW
So, the lower impedance headphone is 10.5 dB louder if it is equally as efficient. Now, with the output impedance increased to 120 Ω, and the voltage to 10 Vrms, the power changes as follows:
32 Ω: 139 mW
600 Ω: 116 mW
The difference has been reduced to less than 1 dB.
With really high output impedance, the 600 Ω headphone will even be louder than the 32 Ω one.