I'm encoding some spoken-word CD's....just curious...

From the same mono source, is a 64 kbps mono file the same quality as a 128 kbps stereo file, using STEREO (not joint stereo) mode?

In other words, if I use the 128 kbps setting, but manually indicate that I'm encoding a MONO file, the end product is a 64 kbps mono file.

I ask because, when using the iTunes encoder, it lists the following as "good" quality:

"128 kbps (stereo)/64 kbps (mono)"

Thanks!

128 kBit/s simple stereo should contain the same data in both channels, so indeed you could achieve the quality using just 64 kBit/s. However, poorly written encoders could choose different lowpass thresholds for these modes. Today when LAME is around there is usually no reason to encode in different number of channels or sampling freq than the source is at.