The effect, when combined with a headphone amplifier suddenly much better sound than the connection to the amplifier or PC, is due to the impedance of the output in relation to the impedance of the headphones. The impedance is the frequency-dependent resistance and the frequency dependence of the influence of the headphone amplifier / output located on the sound.
In general, the impedance of the encountered headphone output is too high, so you have to adjust the level of high (noise) or the sound dark and imprecise because the impedance at higher frequencies is also higher and thus cuts the frequency range. Very rarely, there is also the opposite case that a low output impedance results in a high-pitched height heavy sound. That would be for me but an indication that the headset has been trimmed to hochomige cheap outputs.
Does this mean, then, you should take a headphone amplifier with the lowest possible output impedance, since it all headphones sound good? Yes and no! There is an international professional studio environment a standard of 120 Ohm for headphone signals and high-quality headphones are tuned to. The Beyerdynamics A1 has the impedance of 100ohm and therefore fits quite well to this standard. Since the iPods have overrun the world, this is standard but Makulator. An iPod has a very low output impedance of a few ohms. The problem of an iPod with a high-impedance headphones, although those require little power (good for the batteries) but a high voltage which does not provide an iPod. Therefore, high-impedance headphones sound too quiet on a mobile device and it will be increasingly developed low-resistance headphones. Therefore, the A1 offers itself especially for high-value most headphones.
My test environment is not esoteric high-end but rather the upper price segment. Playback of Apple Lossless via V-DAC and NAD C355 Bee on a Beyerdynamics T1 headphones. The Nad amplifier has a headphone output of 300ohm and it is not out if its signal from the output stage is tapped, or has its own active gain. The change to the A1 in particular give better precision in the bass range and considerably weaker and more difficult to realize an improvement in the space of the signal. I can locate exactly the reverb tails of pulses like percussion that sound more natural.
Now for the price. It consists of a certainly high margin, very good workmanship and (what is more often forgotten) from a comparatively small number of pieces. He is high, going for me but okay.