Are Headphone amps worth the expense?

Aren't there special recordings made for headphone listening?

I think they are called binaural and are made with microphones in the ear positions of some kind of artificial head.

Am I mixing this up with something else?
Didn't the Carver Sonic Holocaust try to eliminate the out of phase stuff coming from the other speaker? Didn't Polk make speakers with double mids and tweets which had a wire pair between speakers to remove this out of phase information mechanically, if you will? The double speakers were located about 6" apart, the distance between the ears so the time cues remained.
This is not a new idea.

Good headphone amps are great if you do alot of headphone listening with a good set of phones. Headphone amps (lots of tubed models available, as well as solid state) are hooked up directly to the source component (cd player, dac, fm tuner, phono stage) or can be be placed on a tape loop monitor output on a an intergrated amp or receiver. It is pretty much a preamp and amp, with a headphone jack.

Inless your Mac tubeamp is an intergrated, you cannot connect a headphone amp. They do not get connected to speaker terminals (or headphone input jacks except for ipod like headamps).

There is a headphone jack on my Luxman 509u integrated amp, and my Beyerdynamic T1's sound wonderful when plugged-in. How does it compare to a dedicated headphone amp? I am not sure how much better a high quality dedicated amp would be, but as I am quite satisfied with what I have I am not going to lose any sleep over it.

Can a headphone amp be fed by the "line out" or "tape out" of a conventional preamp?

I do say tape out in my post. If you use the line out, make sure you don't drive the preamplifier volume up to high. The headphone amp would distort too high a signal. It should be an unamplifiedoutput.

A good quality headphone amp with god headphones will blow away most receivers with a headphone Jack. Thi receivers or intergrateds with a phono stage. You really need to look high and low to find one as good as a standalone, but I have heard they are out there.