A few weeks ago I bought myself some new headphones: some AKG K512 cans from Richer Sounds. These were the cheapest cans available from my local shop, and the salesman was trying his best to get me to buy a better/more expensive pair. I was planning to use them in the office where I am unlikely to listen to a full song without having to interrupt it for one reason or another, so I didn't see the need to splash out on a nicer/more expensive pair. That, and I couldn't make my mind up as to what the right price/results balance was for me.
I normally listen to music using cheap-ish ear buds. I can't really distinguish FLAC from high bitrate MP3 in blind tests. I don't think I have particularly fine hearing. Despite the AKGs being "bottom end", I have gradually noticed an improvement in quality to the music I listen to. It's not something you can notice straight away, but when listening to songs that I have listened to countless times before, I am sometimes surprised by a background instrument or sample or noise that I hadn't heard before.
I wonder, in 6 months time or so, if I shell out for a better pair, will I notice even more?