In reply to:

---

Well, the thing is, it's probably using a full 96 kbps for the one channel.

---

Probably? It had better be, as that's what was requested! Bit rate is exactly that - how many bits are used to encode each second of sound. If you have a mono MP3, then you'll have higher quality than a stereo one of the same bit-rate (but not generally by a factor of two, as the two channels generally have a lot of redundancy).

In reply to:

---

ISTR a bug report that the empeg wouldn't do mono files properly.

---

I've had no problems with my audio books (several dozen hours worth) which are all encoded in mono using lame -mm -V 9. I would recommend resampling down to 22.05kHz, as that's the best frequency response you'll get on FM anyway - no point wasting bits on spurious high-frequency noise! My Harry Potter collection made it in at around 37kbps, and plays fine on the empeg (v2.00final).