Maybe you are write, but can I ask you firstly. Are you won't be able to differ mp3 player something like cowon j3 from any modern DAP for example?Except nothing you wrote in this is true. Lots of statistics with lots of people have been used. So many have said the same thing about in simple cases you don't need it. Guess what, when they try the same comparison blind with level matching they no longer here these simple obvious differences. Everything other than speakers/headphones and microphones are good enough any influence is inaudible to anyone.
Try this one for a simple obvious difference in sound. No way you get fooled right?