MP3 to AAC quality loss question...

It's always preferable to re-rip from the original uncompressed format rather than converting from one lossy format to another. In fact converting from one lossy format to another can result in even more quality loss. It's a bit like photocopying a photocopy, the farther you get away from the original the lower the quality. I would certainly think there's no particular benefit to be had converting from MP3 to AAC but if you want to try then convert a song you are familiar with and listen to it. That way you'll know if it's of an acceptable quality to you personally.

I used to do the same thing. With a good pair of headphones or speakers you can totally hear the difference. Its a thin sound with no richness or punch. Right now I'm going back and redoing all those ones I downsampled. Its a tough temptation to downsample because you can get a lot more music, but its not worth it in the end. Straight from the CD all the way.

Sound quality is highly subjective subject, some people will find 192 KBPS or less perfectly acceptable , others won't. You could try making copies of something you are familiar with at various bit rates and have a listen for yourself. People will have different preferences so it's always best to go by your own ears. If you want to read another opinion you'll get an extensive comparison of the AAC and MP3 formats and bit rates benchmarked against CD format at this link: Planet of Sound - Quality of AAC audio and MP3

You're welcome, I'm glad the article was of some interest. Take care.