Thinking about grado's

I'd get the 125i's personally, but why are you upgrading? Do you mainly listen to rock music?

I'd strongly urge listening to them before you buy, I heard many different Grado's at a HeadFi meet and I didn't like them at all - I'm not saying they are bad but they are an acquired taste IMO. They are quite bright and aggressive.

Yes they do have a love it or hate it kinda sound. Very in your face aggressive sound. I love mine btw. I do have the same pads that come on the 80's and 125's and im not a huge fan. They are ok for a while but after 3-4 hours i have to take breaks. Im going to be getting the pads off the Gs1000's and see how they work.

The 125i's are supposed to be awesome for the price!

What kind of music do you listen to?

i listen to a bit of everything but rock is definitely one of my most listened to.

Well grado's are said to be one of the best rock phones. They are a little lacking in bass for some people. I find it to be tight and controlled not so much muted or muffled. I still would like a little more but I can deal. Not sure if they would be a huge difference over your hd555's. Mabey find used 225's or 325's. I got mine for $180 so deals are out there. Check out Head-fi.

I wouldn't get 125's, get 80's or save for 225's IMO. They will sound quite a bit more forward than your Senns, and the pair will complement each other nicely, but don't expect a huge upgrade.

I would get the SR80. I have some recabled SR60's and they are just excellent for rock and metal - they have so much good midrange. I haven't done much listening on the HD555 but the SR60 sounds waaaay better than my RX900 for most music types other than electronic music.