In headphones your left ear gets to hear the left channel sound and the right gets the right channel sound and its your brain that draws the soundstage unlike a stereo system where the hardware creates the soundstage.
A good sound engineer utilizes the overlap in left and right channel and at times cut off the overlap. While cutting off the overlap will still not keep the stereo system from mixing the two channels when it ultimately hits the ear drums. On the other hand that's an advantage in case of earphones.
I have been listening to earphones ranging from 500 rupees to 60k rupees. A good earphone creates a seamless soundstage. Even great sounding speakers can sound like crap in a normal room not engineered for the purpose. That's where the limitations are overcome by earphones. You leave out the two important variables, spatial position and acoustics.
If the speakers are good they will dissapear from the soundstage altogether and create a holographic imaging which just can't be created with a headphone and its exactly what I'm talking about.
A lot many people will agree that your assumption is simply not true. Speaker setup may provide a concert like experience but earphones place you right in the middle of the band, more intimate in presentation. It's the personal preference. Some like the concert like presentation, while others like to see the detail up close where they can hear the breath of the singer.
I have some great headphones from Klipsch, Sleek Audio, Etymotics, Audio Technica, Onkyo , JVC, Phillips with Cayin and FiiO amplfication but still will say they just can't do what my Stereo set up can.... how it takes you in to the scene in Dark Side of the Moon (SACD) and you are just left wondering how and from where the sound is eminating..... It's like a surround sound without the surround speakers!
Frankly, fiio products are pretty mid fi level. I have Fiio E17 and X1. Both don't even come close to my current setup.
One of the best amp Meier Audio Stepdance, as recommended again and again in head fi, sounds muddy compared to my setup (class A circuit provision). No wonder it is collecting dust in my drawer.
For SACD, this link might help. There is no real advantage of going for it. I have enough space to get SACD albums but I don't see the point in going beyond FLAC.
24/192 Music Downloads are Very Silly Indeed