Grados and classical music.

To my ears from the SR-60 up to the RS-1i the sound of the Grado is almost identical.  The biggest difference is the ear pads.  I think for comfort reasons you should go with a pair of Jumbo pads in addition to the stock comfy pads.  This is because the comfy pads attenuate the treble a bit which is going to affect classical listening.  In fact if you plan on being in noisy environments at all I would consider an alternative headphone.  You simply will not be able to hear all that is to be enjoyed with classical with a Grado in a noisy environment.

You can take a look at the graphs here comparing the various Grado headphones up to the RS-1i:

http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=293&graphID[]=373&graphID[]=393

As you can see by the charts there are hardly any differences between the headphones.  The aesthetics are another matter, but when I had the RS-1i I was underwhelmed by the care that was taken on the wooden ear cups.  My pair seemed rushed and unfinished.

If you are open to another headphone brand let us know and we can gladly make some suggestions.  Otherwise go with the SR-60i and grab some jumbo pads.

IMO if you want Grados for classical the GS-1000i is the best. They have long been considered  here on Head-Fi to be excellent Classical music phone, however the $995.00 price tag may be unfordable but they do show up used on Occasion on the FS forum in the $700.00 price range. My next choice would be the RS-1i and last the SR-225i which has long been considered the sweet spot in the Grado lineup. At $200 it's a bargain and the best bang for the buck in the Grado line up.

My current phone is GS-1000, so that is my answer. (Of course you can get PS-1000 if you have the budget).

It is not until the GS-1000 that Grado phones finally can do the large scale works better than the others.

PS500 is also a good pick if you want a broader fit of classical music.

The traditional Grado product line from SR60 to RS1 are great for small scale works but may be too crowded for large scale works (you can still get all the detail, but just too crowded).