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Amping headphones - Focusrite 2i4 and BeyerDynamic DT-770 compatibility
Old 14th October 2013
Here for the gear

Amping headphones - Focusrite 2i4 and BeyerDynamic DT-770 compatibility

Hi everyone,

I am a recent, proud and satisfied owner of a Focusrite 2i4, and I would like to acquire a Beyer Dynamics DT-770 to do some mixing with it. However, I don't know what impedance to choose: 32, 80, 250, even 600???

I have already checked that massive guide but I don't know whether the 2i4 will prove able to amp up to a 600Ohm.

What do you guys reckon?

Thanks in advance for your answers,
Old 14th October 2013
Like virtually all USB powered interfaces, the Focusrite 2i4 has limited output voltage swings and power (24 mW into 32 ohms). It does have a low impedance headphone output (less then 12 ohms output-Z) and will work best with the 32 ohm version of the DT-770 (it's designed for low-Z phones that don't require wide voltage swings). The 2i4 is designed to work best with high-efficiency phones having an impedance between 24 (min) and 62 ohms.

The high-Z versions of the DT-770 (250 and 600 ohm) will work, but will not produce very much output volume. You need a headphone output with a much larger voltage swing, or an external headphone amp to boost the voltage to use the 600 ohm phones.

The (32 ohm) DT-770 Pro will reach a peak SPL of 110.5 dB at the clipping point of a 2i4 at a peak power of 24 mW per channel. That means you could listen at average (RMS) levels of around 99 to 102 dB SPL. That's fairly loud, and safe for short periods of time, but is much less loud than the levels that a higher effeciency headphone OR a more powerful amp can reach.

For instance, the (24 ohm) Sony 7520's are about 12 dB more sensitive than the (32 ohm) DT-770s. That means the Focusrite 2i4 can drive them to peak SPLs of 121 dB. Not that you'd want to listen at those kinds of SPLs.

The Focusrite low impedance output will properly damp even low-Z phones like the DT-770 Pro (32 ohm) or the Sony 7520s unlike some headphone amps that use low powered op amps and have series current limiting resistors (some Rolls multiple headphone distribution amps come to mind). When used with a "higher-Z" amp, the 600-ohm phones will have a better damping factor (than low-Z phones) and can sound better. With a low-Z output (like that on the Focusrite) there is very little or no difference in the sound quality between the various impedance versions of the same model headphone. The 32 ohm DT-770s will sound great.
Old 18th September 2017
Here for the gear

I just registered my self on this website, just to put this post and write BIG THANKS for that compatibility review from Lotus 7! Great, clear and helpful stuff. RESPECT &
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