Originally Posted by icfireball
The music you download from iTMS is ~CD quality. When you burn that to an Audio CD, you again have music that is ~CD quality, only limited by the original quality of the track you are burning. The quality difference between the protected version and the original version is almost nothing, if anything at all.
I posted this listening test
a while back, and ran a poll associated with the test here on AppleInsider. Most people had no difficulty at all telling a first-generation 128 kbps AAC file from a 128 kbps second-generation of the same (meaning that the first gen was decompressed and then recompressed, the equivalent of burning a song to a CD and then re-ripping it to the same bit rate and format).(Damn AppleInsider's search engine! Forget just the old post of mine I'm talking about, the search claims there are no matches at all for "lossy compression" in the whole damn collection of forums, except for some bad joke about the 'rm' command.)
First of all, a lot of people would argue the "nearly CD quality" claim. Personally, I find the quality of most stuff from iTMS pretty decent, but "nearly CD quality" is stretching it.
Second, there are some special problems which arise from multi-gen decompression/recompression cycles using lossy compression. Maybe I'll get into the technical details later, but for now I'll just say it can be an ugly thing. The best way to circumvent the effects of two-gen compression is to use a higher bit rate for the second generation. For my own tastes, I'm pretty pleased with using 192 kbps for the second pass. Just going up that 50% in bit rate seems to make a world of difference.
For instance, with some songs I've purchased on iTMS, I've wanted to add a fade-in or fade out to cut off a spoken intro to a song, dragged out audience applause in a live recording, etc. That means decompressing so I can use an audio editor, then either recompressing or dealing with a big lossless (AIFF or Apple Lossless) file as the result. I chose to go with 192 kbps AAC for such things, and I'm pleased with the results.