I've been listening a lot lately to a disc of two Beethoven string quartets by the Petersen Quartet. I have other versions of these quartets, but this group really brings out the beauty of the music, especially in Op. 132. I don't hear the same things in my other recording, even though they are playing the same notes. Interpretation, skill and recording quality make a huge difference. I ordered another of the Petersen's Beethoven discs this morning (they've recorded about half of the 16 quartets and plan to do them all).