There's a lot of commonality between the images, http://g-ecx.images-amazon.com/images/G/01/common/sprites/sp...
Even with Base64 encoding, much of that commonality would remain and thus I'd think that if you had all these sprites as SVG in a single file, as Data URIs, gzip would do a very good job indeed on the CSS file.
In a PNG sprite I wouldn't be so sure.
There's a lot of commonality between the images, http://g-ecx.images-amazon.com/images/G/01/common/sprites/sp...
Even with Base64 encoding, much of that commonality would remain and thus I'd think that if you had all these sprites as SVG in a single file, as Data URIs, gzip would do a very good job indeed on the CSS file.
In a PNG sprite I wouldn't be so sure.