Hello,
I have the Grado Sr-325e, PS500e, and two GS1000e headphones. I thought I'd take a moment to give some impressions.
SR325e - very similar sounding to the PS500e - the 325e is an exceptional value when considering how much more the PS500e costs. That said, the PS500e has a slightly better sound to my ears. The sounds are a bit more vivid, the bass is a touch more plentiful, and the overall sound is a little warmer than the 325e. I should mention, the PS500e improves over time and was not great out of the box. I should also mention I find the 325e significantly better than the 325i, which is too bright and recessed in the mods/vocals for my liking. I have not used the 325e long enough to know if it will benefit from burn-in. The size of the soundstage is very similar in both the 325e and the PS500e. I have the luxury of owning both, but I would not hesitate to recommend the 325e to those who may not be able to afford the PS500e. The 325e is literally 95% as good in my opinion. I would say the Grado 325e and PS500e are slightly bright but the PS500e is closest to neutral of the Grados I have heard. If I could characterize the P500e, I'd say it's almost hyper-real - like a painting that uses very bold colors; also to continue the painting analogy, the soundstage is dense but reminds me of a 4:3 ratio.
The GS1000e - you note that I have two. The first unit I purchased really lacks bass, punch, and impact. The midrange is very grand - larger than life. But here's what I find interesting. I wanted to see if the lack of bass was specific to my unit or the same as others so I purchased a second unit. The second unit has slightly more impact and slightly better bass, but not substantially different. Where there is a slight but clearly perceptible and beneficial difference is the upper mids. The first unit has brighter (strident) upper midrange where the second unit (which happens to have a different look by the way) has a more neutral and balanced sound. The upper mids are not strident and in the scheme of things, though both GS1000e units sound similar overall, the second unit is clearly better, at least to my ears. Also, where the soundstage of the PS500e is like a 4:3 ratio picture, the soundstage of the GS1000e is more like a 16:9 ratio - very wide. The midrange is better than the PS500e and 325e and one of the best in my mind. BUT, I would take the PS500e over the GS1000e if I had to choose, price not being a consideration. The mids of the PS500e are excellent, but not quite as good as the grand GS1000e, but the overall sound of the PS500e is a bit more crisp and the bass and impact is much more present. Of course, I cannot ignore the fact that there maybe significant variations in sound from unit to unit.
One thing I'll close with. I have many flagship headphones, and I never thought I would feel this way, but I would take the PS500e and the GS1000e over most if not all of them. The bass on the Grado may not goes as deep as others, and some headphones may have even more impact, but the clarity of the Grado is signficantly better than most headphones, and to me, that's extremely important. I think, in part this is due to the brightness of the Grado; it may also be due to the fact that the Grado doesn't over-emphasize the lower midrange, which I feel many high-end headphones do at the expense of clarity.
Sorry for the lack of structure, but just thought I'd offer my insights for those interested in knowing how different Grado models compare. Oh, one more thing. The GS1000e sounds nothing like the GS1000i that I heard. The I had a "V" shape frequency response - recessed mids but very strong midbass, where the GS1000e seems to be slightly midrange-centric.
