Although eMusic is a great service—for a flat monthly fee, you get a set number of downloads per month of DRM-free music tracks—it’s about to get better. Or maybe worse, depending on the breadth of your musical tastes. Today eMusic will announce that Sony is adding its back catalog of songs to eMusic’s library. The bad news is that eMusic also plans to slightly raise prices and/or drop the number of downloads per month. Even if it works out to between 50-60 cents per track, though, that’s still far less than iTunes Music Store or Amazon, and probably the cheapest way to grab music from Sony artists without resorting to piracy.