FiiO E07K Andes portable USB DAC Headphone Amplifier Amplifier (3.5 mm Jack Black) (Electronics)
I bought the headphone amplifier actually for my new Beyerdynamic DT990, but was compared to the sound card of my notebook (Acer Aspire V5 model of the middle class) do not hear much of a difference from my smartphone, the device is not recognized, s