I was at a local surplus store today and I got two [LM386N](http://www.ti.com/lit/ds/symlink/lm386.pdf) ICs. I thought I could make a really simple headphone amp out of these. But I have no idea what the wattage of a normal headphone amp is.

These LM386 are rated 325 mW at 8 Ohm, which should be about 81.25 mW at 32 Ohm load.

Is 81.25 mW a reasonable power for a headphone amp? How does that compare to, say, a Laptop's 3.5 mm jack's power; how about an iPhone's?