I have trouble telling the difference between good mp3s and other sources on any of my systems, at least for the pop/rock types of tunes I occasionally buy in mp3. These are typically not audiophile level recordings however.
Never compared on earbuds but I am doubtful I would hear any difference that mattered at least with this kind of music.
I suspect Ipod digital out as a source to another device to make the sound could work pretty well, but then we are moving away from using the ipod for what is is designed for, ie producing portable music itself and towards making it just a source device for system that is better suited to make music more like what we are used to hearing on our good systems.
Never compared on earbuds but I am doubtful I would hear any difference that mattered at least with this kind of music.
I suspect Ipod digital out as a source to another device to make the sound could work pretty well, but then we are moving away from using the ipod for what is is designed for, ie producing portable music itself and towards making it just a source device for system that is better suited to make music more like what we are used to hearing on our good systems.