I like the SR325is , it just need a little more uplifting bass. The RS1i sound signature is picky on the Genre of music. I find it perfect for male vocals like Tonny Bennet or female voices like Toni Braxton, for Taylor Swift (not a fan), OM..........
If Grado can put the 325is mids/high and combined it with PS500s bass... That is my ideal sound signature... So far the PS500s comes close to what I prefer.
Wha? The SR325is's highs? They were the most fatiguing painful headphones (not just Grado) that I've had on my head. YMMV of course, but thinking of the SR325s still has the hairs on the back of my neck stand up at attention. I owned them for a month and ditched them for the RS1s and never looked back. Sounds like your RS1is had "issues" or needed burn-in?
For those who think the RS1s have too much treble energy, then the PS500s would definitely be the way to go.