I can't really hear the difference... So that's why I also use the option that iTunes changes the music I put on my iPod to .AAC 128kbps (.aac is better than .mp3, and 128kbps MP3 sound horrible compared to 128kbps AAC). I don't hear a difference and it saves a lot of space!
I have Pro Beats by Dr Dre and even HQ and 320kbps sound different. They are AMAZING! I recommend getting beats, there are other cheaper kinds. They've made me enjoy a lot more music because you can actually hear the production, and they also let me know when something is really bad.
My Songs Are all 256 ~320 kbps
But In My iPod I Put the Option to Convert to 128 Kbps ACC because of Space (I'm Cheap and I Bought A 8GB iPod )
There is a Difference though.
I also have an OCD (obsessive controlling disorder or something) about my iTunes librabry being on point and punctual, and RIGHT, lol. So when I download .m4a(<- iTunes plus) it's all perfect and nice :'] and in the best quality lol. and sis I'll hint you something on the wallll ;D