I do use an amp with my Grados (RS1 now, HF2 previously) and they do help bring out the bass but I don’t consider an amp an absolute must for these headphones. Neither of two two cans sounded bad out of an iPhone when I hooked it up for fun.
If you want to get more of them while remaining portable, consider a cmoy amp or a Fiio E11. They’ll fill out the sound and improve the dynamics and punch but you’ll still get the gist of their sound just plugging it straight into the iPod.
Do most of you use an amp with your PS500s? How bad are they direct from an iPod? I know I'm probably going to get flamed horribly for even asking this, but I like having flexibility.
I'm used to my JH16 IEMs, but was thinking about picking up some of these to give my ear canals a break. Given the relatively low impedance of the PS500s I can't imagine they'd be too bad.
Any advice would be appreciated!