I've had this a while now, and while none of my headphones that I listen to on my S8 need an amp, this little guy plays a key role in my home theater. I use it on the zone 2 out of my Denon receiver to feed my CLEER-based wireless Sennheiser theater headphones. Provides a nice, clean signal and the bass boost is appreciated for movie watching. Solid little piece of equipment.
Also, if all the talk of amps has made you wonder if you somehow need one, or if it would make a difference on your headphones, this is a very inexpensive way to find out. You probably don't need one, but $35 is pretty easy on the wallet to try.