[TheChosen0ne]

When I got my first audiophile headphones 1 1/2 yrs ago with the HD600 with fiio e17+e9 I couldn't tell the difference between that and the ipod earbuds but after 1 month I switched back to the apple earbuds and the difference was HUGE.  I got disgusted with those earbuds that I threw them out of my window.  However I never really thought about the difference between a good and bad quality song while just listening with the HD600.  I watch old music videos on youtube that have been out for 4+ yrs and listen to the same song I downloaded on itunes and I really can't tell the difference between the music video and the song on itunes with the same headphones. 
 
 
Also a random thought, I just got my new headphones today, Grado SR325is and just like when I first got my HD600s, I can't tell the difference between them but after listening only to my Grados for 1-2 months while listening to music 6-15 hours everyday, I will go back to the HD600s and hear the difference.

 

[NA Blur]

Always give yourself a month to fully appreciate a headphone.  Too often we buy on impulse or react negatively to a headphone the first few days we own them.  This is because our brains apply a filter to the sounds we hear and as we become accustomed to one set of headphones a different set will sound bad.  This is not always the case, but it does supply one reason many of try to measure how a headphone sounds rather than list our first impression.
 
Here are a few links to samples that should test your headphones for clarity, bass extension, treble, and distortion.
 
Dream Theater ( Metal )
https://www.hdtracks.com/index.php?file=catalogdetail&valbum_code=HD016861776565
 
Coleman Hawkins ( Jazz )
https://www.hdtracks.com/index.php?file=catalogdetail&valbum_code=HD00011105018425
 
Jackson Browne ( Rock / Folk )
https://www.hdtracks.com/index.php?file=catalogdetail&valbum_code=HD081227976712
 
I do hope you end up enjoying your new headphones.  There are things I really like about Grado headphones, but I cannot wear them as the treble and comfort is poor.