I have a question. What would you think would be better sounding for a mono audio book:

Lame 3.96 with --alt-preset 32 -m m

or

WMA 9 with a 32 bps 22khz mono setting

I'm just curious. I tried both with audio books and I couldn't find much of a difference but I really don't have a golden ear. I know I'm have Lame compete at ABR and WMA8 at CBR. Is any ABR format better than a CBR format or has WMA been so optimized at low bitrates it can overcome this problem.

BTW, for those who say upgrade to WMA9, I can't. I have a Win 98SE and there is no new encoder for us oldies.

If its too close to call, I'll choose the Lame because I'll probably find more players that support it at a low-rate VBR than WMA in general.

Try dBPowerAmp with the WMA9 codecs (available @ www.dBPowerAmp.com in the codecs section) and it should work fine. I use WMA9 VBR at Quality 10 for audio-books, and it usu. avgs 32k or really close to it. It's miles cleaner (fewer muffled highs) than any MP3 encoding I've been able to achieve, and I've spent hours testing with LAME, etc.
Try it yourself. I'm v. interested in your results, esp. if you find an MP3 setting that's better

Speex or acelp.net (WMA container)

Unfortunately I didn't mention that the end product will be a Rio Karma. I'm pretty sure Rio can't do Speex or acelp.net. Am I wrong about that?

The Rio Karma unfortunately doesn't support Speex, but it does support Vorbis.