I've bought an audio interface, that is: Tascam US-2x2. Now I want to buy some nice studio headphones and I wonder how high I can go with impendance in those headphones to still get a decent signal level.

The manual says:

Headphones output (PHONES) Connector: 6.3mm (1/4") standard stereo jack Maximum output US-2x2: 18 mW + 18 mW or higher (THD+N 0.1% or less, into 32 Ω load)

I heard that impendance of out should be at least 8 times lower than headphones impendance. Does it mean, that I can safely buy headphones with impendance up to 32*8?

I'm about to buy BEYERDYNAMIC DT 770 PRO 250 Ohm. Will my audio interface be able to give it enough power?

2 Answers 2


You won´t break anything by doing so.

The output power is governed by ohms law, 18 mW at 32Ω will result in something around 2 mW at 250 Ω so your phones would be a little bit on the silent side.

For moderate loudness the DT 770 PRO 250Ω will need something around 2 mW.

Of course you could add an headphone amp like the Behringer HA 400 but I strongly believe that this will definitely not work out. The difference in audio resolution you get by using the high impedance version is minute and by far outnumbered by the loss in quality introduced by the HA 400. That way it won´t work.

The 80Ω and 250Ω have better insulation from surrounding sound and longer cables, thats an argument. But even the 80 W version will be relatively silent, getting a maximum of 7 W.

  • Thank you for answer! Will something like BEHRINGER HA 400 do the work without adding noise? And is there really a difference for mixing between those 80ohm and 250ohm DT 770 PRO ?
    – Raven322
    Dec 25, 2018 at 1:10

The spec. tells you nothing about the output impedence of the interface. It tells you it will deliver (at least) 18mW per channel INTO a 32ohm load before distortion and noise exceed 0.1%.

18mW is not a lot. (You're not GOING to get a lot of power from an interface designed for USB powering.)

The beyerdynamic DT 770 PRO is available in 250ohm, 80ohm and 32ohm versions. The 32ohm version is specified for 'mobile' rather than 'studio' applications, but seems to be what Tascam had in mind as suitable for the US-2x2.

Higher impedence isn't 'better'. Higher impedence MIGHT mean a lower-mass voice coil with better response. But that makes no difference if the volume's so low you can't hear it!

But don't panic. An additional headphone amp can be cheaply added to your system.

  • Thanks for you answer, Laurance! Do you think that smething like BEHRINGER HA 400 would do the work with 250ohm headphones? or even more ohm headphones (like 600)? And what do you think about plugging in to my interface 80 ohm headphones for studio application. Are 80 ohms enough for studio quality recordings?
    – Raven322
    Dec 24, 2018 at 15:55
  • The Behringer should be OK. Amplifing a headphone feed isn't a difficult job. But try without first. You may get a nice surprise. The numbers don't mean THAT much.
    – Laurence
    Dec 24, 2018 at 23:11
  • Ok, thank you for answer, Laurance! I'll try it out without Behringer at first.
    – Raven322
    Dec 25, 2018 at 1:03

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