Why do headphones sound so good...

Well Amplifying an Ipod through a good resolution system will never sound as good as it going through headphones #1, To much exposure to the lower quality source in most cases...

I thought I would never beat headphones myself, mainly they are just easier and you can get good quality cheaper, and main thing is you are not fighting the acoustics of a large room and airspace, they are 1" from your ear drum, huge difference.

However after many battles, I have found the solution that stomps my Grado's, and thats Excellent room treatments with very efficient speakers and tube amps... Now I feel like I have more pressure and smooth controlled sound than even with headphones, and yes it even sounds better like a live venue in the house.. I have people tell me all the time they can't believe how clear and balanced even compared to headphones my system is now.

So room treatments will be like the earmuffs sealing to your ear if your willing to truly solve the issues with an audio system, its 9 times out of 10 the room environment not the speakers, and thats where the headphones have one up in the first place, cause they don't compete with a crappy room!

Why do headphones sound so good...
Although the responses thus far seem diverse, I can honestly say that I agree with every single one of them to at least some degree. To add to the already excellent insights given above (not a loser in the whole lot, imo), I would say:

--Headphones USUALLY are able to retrieve more sonic detail than all but the very finest loudspeakers, as Itball mentions.

--In my experience, headphones do NOT provide a convincing soundstage, presumably for the reasons Shadorne alludes to.

--I personally own both Stax Lambda Signatures AND Stax Lambda 404's (it's a long and embarrassing story as to why I own both sets of cans....), and the speakers I own seem to outperform them in every arena-probably even including retrieval of detail(although I'd like to do more critical listening to test this point). That is saying a lot considering the legendary status of these headphones--Stax makes only one model of higher caliber, which is the Omega II's.

I agree with most of what has been said here regarding both the pros and cons of headphone listening. Just depends on your preferences, and I’m willing to accept their limitations; everything has weaknesses. Personally, I do all of my critical listening through headphones, and I couldn’t be happier. They involve me more in the music than any speaker-based system ever did—and I’ve owned some hyper-expensive ones. Granted, I’ve got a pretty costly rig, but, still, it’s a fraction of the price of my last speaker system.

I believe that it is much easier to reproduce life-like dynamics with phones than with speakers, probably for the reason oft stated above, that there is less air to move. Some experts believe that it is the gulf between the dynamics of live versus recorded music that make it easiest for us to discriminate between them. If that is true, then it follows that phones would get there easier than speakers and be preferred by many.

I also agree with most all of the above.

I would add excellent headphones have very little phase shift, as their single diaphragm moves nearly/almost as one solid piston through the range of 200Hz to >8kHz.

In that same range, most all speakers have hundreds of degrees of phase shift (time delays), which change with the frequency being reproduced.

A lack of time-domain distortion can also be called a high level of time-coherence. This is not the same as phase coherence.

Time-coherent operation goes a long way to revealing the touch on any instrument, the enunciation and inflection in any voice, intense dynamic contrasts, and clarity of the individual artists, almost regardless of what those headphones might be plugged into.

I use the word 'any' in the last sentence, for you should be able to track those characteristics of the performance through any tone range/any performer. Also, any image, as odd as it may be to hear it inside your head, should be stable in any tone range.

If you encounter a tone range where something isn't right about one of those characteristics, you are in a range where phase shift and possibly other distortions are high.

My first truly involving headphones were Koss ESP-9's. Still have them, now with a dead power supply, but someday...

Best regards,
Roy Johnson
Designer
Green Mountain Audio