As long as the recording has no audible MP3 artifacts, I don't really see the problem.
There's an increased chance of encoding/transcoding artefacts when the OP encodes their $30 CD to mp3
How does a nominally transparent codec suddenly lose it's ability to determine what's audible and what's not, just because another codec was used somewhere back in the processing chain?
If you cannot distinguish a given-size E from same-size F at a certain distance, that does not mean you cannot tell an E from a ? (here I just 'doubled the artifact', right?)
Edit: have a look at http://www.hydrogenaudio.org/forums/index....showtopic=32440
then the codec has suddenly forgotten that F -> ? is not transparent (which it knew in the 1st pass).
In other words, is an artifact difficult to encode? (where "difficult" means that an input signal has a high chance of being distorted after encoding to a certain bitrate X). Will a ringing artifact from pass 1 be doubled or tripled or quadrupled by a second pass, because it is essentially new and difficult information? The short answer is "Yes"
Does *anyone* have tracks that are not altered by mpeg encoding?