I've owned a pair of SR80s for years now, they recently went out of commission due to a fall I had while listening (oops). Bent the head of the 3.5 and the cord got sliced by my chair. First time I was legitimately heartbroken over the loss of a inanimate object. Eventually I scraped the money to buy the sr80i. Nothing too new and improved after breaking them in, from memory (and without amping) the sr80i captured the same magic in my music as the 80s did, no more no less and that's not a bad thing. Immediately I was wondering what the point of the upgrade was anyways. It wasn't until hooking it up to my cmoy that it became apparent. I never amped my 80s too much because there wasn't much of a noticeable difference to me, it became a little more flat and drowned the bass slightly (even after my mods), but it didn't improve or detract from the sound so drastically that I needed to take it with me everywhere. When I amped the 80is with the same amp though, it became slightly unbearable. It was just too bright, and I actually prefer the 80s for that reason, but when I say too bright, oh my.
One of my first purchases with my upgrade in payscale was of course headphones. After my first paycheck I immediately bought a pair of AKG K702s and Sr325s. Big mistake, but a great one at that. It wasn't until I broke the Sr325s in that I finally caught the "Grado upgraditis". I've heard my friend's vast collection of headphones, and because I could only detect slight differences between them all, I never thought I was that much of an audiophile, that my ears had already been numbed enough from all the years of 10$ ear buds and loud gaming speakers. But after spending extra time with the 325s, I want more.
I dont know why I decided to rant on like that, Im at work and theres a dead period right now. I guess all I can say is if you do like grados, be wary of upgrading to anything higher than the 125s, make sure you have money to spend afterwards because you'll get addicted.
Oh, and back to the original topic, you really don't need an amp for the 60, 80 and 125, I mean it's all going to be preference, but it won't do so much that it'll be worth carrying around with you. And DO NOT amp with the fiio e5, not saying it's a bad pocket amp (great for my IEMS), but it kind of trudges over that sweet grado sound.