it's hard to say. I don't know if it's just me, but the difference between the two are really miniscule. We are splitting hairs at this point, but that is what head-fi is all about. generally we are talking about a less than 10% difference. If you prefer a slightly brighter sound then the 325is will be better for you. But the PS500 is not shy in the treble either. I had to listen very very carefully to hear a difference, and even then it's not noticabel on all recordings. It could be that the music I listen to doesn't contain a lot of detail above 5 kHz to begin with and makes both phones sound very similar.Having said that, my wife tried the PS500 and loved them right away. Her first comment was "the are really warm and smooth". She doesn't listen to a lot of music with headphones but she said she would choose the PS500 over all the other Grados, which she uses every so often. I have spent a few days going back and forth between the 80i, 225i, 325is and PS500. They are all very very similar. If I was not serious about listening to music I would say none warrant the extra price over the 80i. Unfotunately, or fortunately, depending on how you look at it, the only way to know is to buy both and then sell or return the one that doesn't suit you.
