[ryerman]

Hi MrSinatra

I bet it's a big job converting your library and I hope this is the worst of any problems!

My system basics are in my signature but I've attached an Info Report, in case it's helpful.
Otherwise, I'll hold off from any detailed response.
Instead, I may have a work-around for the undesirable behaviour of your example .m4a files.

Try the attached files.
They were transcoded from your example mono .flac files, but into stereo .m4a.
For me, the weird playback issues disappeared and the bit rates are shown consistently in Winamp. They agree with Mp3tag (+-1 kbps). But still, not with the .flac originals.

Afterwards, if you still want, I can answer your questions.

I think 1 or both of 2 things are happening:
1. GIGO: the flac files are faulty (even though they play in Winamp) and therefore the resulting .m4a files are faulty.
2. Winamp doesn't like mono .m4a.

But I'm just guessing out loud.