FRED
HI: This is from the web site.
In the tradition of high-end audio systems, critical components are joined with thick, point to point traces for maximum conductivity. The amp can also be used to power speakers, not only headphones. You really will be surprised at how much power it can output for such a small device. This amplifier works great with all types of headphones including those made by Grado, Sennheiser, Koss, Sony, Etymotic, Shure, AKG, and many more. Please do this amp justice and use it with a nice pair of headphones.
Most portable devices have an output power between 5 to 10 milliwatts which is too weak to power a decent pair of headphones. This amplifier has a true output power of over 200 milliwatts RMS (almost 1/4 watt!), making the music louder by a factor of 610%. The signal to noise ratio (SNR) is 100 dB. Actually, with the volume turned on maximum, and no music playing, there is no static sound or hiss, which is something desirable. Building an extremely quiet, low distortion amplifier was a high priority.