There is a distinct difference, however whether it's perceivable, and how much, depends on many factors.
Unfortunately I can't access the full articles, however here's the abstract of a very relevant article, emphasis mine.
Mp3 compression is commonly used to reduce the size of digital music files but introduces a number of potentially audible artifacts, especially at low bitrates. We investigated whether listeners prefer CD quality to mp3 files at various bitrates (96 kb/s to 320 kb/s), and whether this preference is affected by musical genre. Thirteen trained listeners completed an A/B comparison task judging CD quality and compressed files. Listeners significantly preferred CD quality to mp3 files up to 192 kb/s for all musical genres. In addition, we observed a significant effect of expertise (sound engineers vs. musicians) and musical genres (electric v.s acoustic music).
So, this study finds that the answer is that above 192Kbit/s, further gains depend on the genre and the training of the listener.
Furthermore another study finds that perceived quality depends on whether you are using headphones or not:
The impact of using loudspeaker versus headphone playback on the subjective quality of compressed audio is investigated. It is shown that reverberation and to a lesser extent cross-talk, which both are introduced naturally in loudspeaker playback, can effectively hide coding artifacts.
This other paper describes the differences between different bitrates and different ways of testing. In all cases it shows a very minor difference between 192Kbit/s and 256Kbit/s and basically no difference between 256Kbit/s and 320Kbit/s.
As you can see, above 192Kbit it becomes quite hard to tell the difference.
answered May 15 '11 at 14:52
Have you tried the latest group of services, specifically MOG? If you haven't, I'd recommend giving them a shot just to see what you think.
The thing is, they offer something for everyone. Some people might rely solely on their suggestions, others might use the social aspects and follow the playlists of some friend or musician that they enjoy. Some folks (myself included) just like to browse on our own, saving artists with potential for further listening later.
It's kind of like being in a huge record store, except you get to open everything and play it is much as you want.
A few examples: I started a playlist using only songs containing the word "Hallelujah" in the title. I ended up with a broad range of songs I enjoyed, by diverse artists such as Jeff Buckley, The Head and the Heart, The Helio Sequence, Jens Lekman, Rita Coolidge, Thao & Mirah, and Rufus Wainwright. Another time I searched artists with names having to do with snakes. I ended up with a playlist featuring The Snake The Cross The Crown, Cobra Skulls, Viper Creek Club, Python Lee Jackson, These Arms Are Snakes, and The Dayton Sidewinders.
The freedom to have access to all this music, with pretty high sound quality, for less than the price of an average album on iTunes, is phenomenal. Yes, I realize that I don't actually OWN any of this music. I'm merely renting it, or the ability to access it any time I want. But the important thing is that I'm enjoying it, and I can always go out and buy my own copy if I feel the need.
I guess the point is that you don't necessarily need the service to spoon feed you music if you prefer to take charge and do it yourself.