Headphone preamp question...what are they for?

[MusicDirector]

As I was hunting for a headphone extension cable with a 1/4 inch male end and 1/4 inch female end, a question crossed my mind. If every piece of audio gear has a headphone jack (Receivers, CD players, Amps, Tape decks, etc) then what are all those headphone amplifiers I see and hear about for? I certainly would not want to play my headphones loud. I'm not knocking them or anything, I just don't know why someone would need one unless they have no way of using headphones, but then they would not have any audio gear if that's the case. My logic may be too old school on this, but it's the way I was raised.

 

[Shadowfax]

Problem is, not every component has a Headphone jack, or internal amp to drive them. It seems like lower end gear has them while higher end gear, not all, omit them. My older Hafler Pre-Tuner has one, and my Rotel receiver, but my CDP and VAC have none.

So you would need one if wanting to listen to cans if your gear does not provide the ability and then in many cases, the standalone units will sound better than the integral ones because in most cases, they were a value added feature of sub quality, like many other features in an HT Receiver.