Hi, Im kinda new, and I know a little bit about recording, audio, and all that other stuff, but Im no where near a guru, so this will be a good site for me to learn.

I have a pretty simple question that I was wondering about. As Ive heard, WMP claims that its WMA's sound better than MP3's at the same bitrate, and we also know that AAC's generally are slightly better than MP3's at the same bitrate (but cant tell once you pass like 160).
We also know that transcoding a lossy to a lossy (like 256 mp3 to 192) hurts quality alot.

I was wondering, (theoretically) if you had a 192kbs WMA file, and you transcoded it to a 128kbs MP3 (using WMP for example), would you get more quality out of the 128 mp3, than if you had transcoded a 192kbps MP3 into a 128kbps mp3?

This could be done in many scenarios. For example, a 320kbps MP3 encoded with lame, transcoded to 128, compared to a 320KBPS encoded with itunes (inferior) into 128kbps.

So in laymens terms, although bitrates may be the same, does transcoding from a higher-quality/better encoded file give you more quality in the end?

Will a better source give you a better encode? Yes.

Microsoft may say that WMA is better, but they are in the minority; that said I'm unfamiliar with the newer codecs. Guruboolez did perform some tests converting from various source types using various encoders, and IIRC it often appeared better to encode from one format to another, rather than the e.g. MP3 to MP3. Again though, the better the source the better the encode.