Good question...mostly all of the above.

I have killer high end Sony earphones that just deliver that sound right into your head, I also play new Cds for review everytime I leave the house on the car (rarely play back catalogue, always reviewing...) and of course I work at the PC for 5, 6, 8 hrs a day, so new music is going all the time.

For my PC I have nice 2.1 speaker set up with a great sound card.

And you are right, music thru different devices can give different results. The best albums are ones that sound killer on all 3 outlets.