Herb, do you use WavePad for your 'mastering software'?
Yes.
It's a good program and I use it to listen to and work on my exported waves.
In Wavepad I trim the start and the end, and I also run the normalize function on the wave.
After I have done those chores, I convert it to mp3 in Wavepad.
Wavepad seems to have a player that sounds extremely close to my DAW, which is always a good thing. In other words, it doesn't sound to me like it's adding any color to the sound. AND.... I can't tell any sonic difference in Wavepad between the final Wave and the mp3 that came from it.