MP3Doctor - Resample
Resample feature let you adjust CHANNELS (mono or stereo), QUALITY (high,
medium and low), BITRATE (from 0 kbs to 320 kbs) and SampleRate (from
6,000 to 48,000 hz) - a CD has 44,100 hz-.
More BITRATE and SAMPLERATE = MORE quality = MORE disc space used
The most common settings are 128,000 kbs and 44,100 Hz in Stereo.