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I want to buy a pair of headphones with these stats: Sound pressure level (SPL) 97 dB (SPL) at 1 mW, 300 ohms
And I have this audio interface but I can't tell by the specs if it can power these headphones. http://us.focusrite.com/firewire-audio-interfaces/saffire-pro-24-dsp/specifications
Basically, are audio interfaces equipped with a high output so they can power any headphones or is an amplifier a must-buy element for high impedance headphones?
Thanx
"Power" isn't really the issue. Certainly, most interfaces can offer enough wattage to cause ear damage, theoretically.
However, the actual power is not determined by the HP-output alone, but by the headphones' own impedance as well: if it's substantially larger than the output impedance, then
P = U2 / Z
where U is the (RMS) output voltage of the interface; this is really the relevant parameter of a headphone-out's performance. Now, 300 Ω is a pretty fat impedance, so this means you need a higher voltage to get the same power than you would with lower-impedance headphones. You should definitely not expect very loud volume range when connecting these phones to an ordinary interface; in particular USB-powered models have a tendency to not offer very impressive voltage. For a FireWire model like the Saffire-Pro however, you can expect more generous output.
Definitely the headphones will work, the only question is whether they'll be loud enough for you. High-impedance phones aren't really meant to be driven very loud anyway, so if you need it loud another pair might be more suitable.
