I opened a thread before because I was thinking of getting the HD's 650 or the DT 990. But I changed my mind after reading about the HE-4. The problem is that even being a pretty low impedance cans (38 Ohm), they seem to be pretty hard to drive properly. More concretely I've read about the Fiio E7 not being able to drive them (sounding muffled and not better than Sennheisher's HD 580) in comparison to a wonderful sound using a EF-5.
I have a Cretive Titanium HD soundcard with the following headphone output:
Headphone (330Ohms): 1Vrms,117dB
And I'm worried thinking if it would be able to drive them correctely too. The E7 impedance limit is 300Ohms, so the problem wasn't about that. Power I suppose?
Ok, the E7 characteristics:
Output Power: 150mW (16Ω); 16mW (300Ω)
Now if I want to compare both amps (I will assume that those mW from the E7 are rms! although I'm not sure!):
Titanium HD: Power = V^2/R = 1/300=3mW (@300Ohms); P=1/16=63mW (@16Ohms)
So, much less than the E7 (edit: and less than an E5! 12mW-150mW @16-300Ohms. And the E9 gives 1W @16Ohms with just 2Vrms. There's something wrong... Those Watts in E7/E9 specifications aren't in rms and are just peak values?).
Am I right? If that's the case I assume that buying those headphones in order to use with my soundcard is out of the question and I need the EF-5 or at least an E9.
Thanks in advance!
PS: I do not know if there's any way to use this to make an idea, but the efficiency of the HE-4 in the specifications is 86 DB.
Original post what I reffer before: