>>No kidding? He replaced the Bose HU? Or did he have a Mazda HU? I had thought that the Bose was standard but perhaps it was just standard with the package that I purchased. If he did have a Bose, is the Pioneer unit that he selected significantly better? <<

I had a Mazda HU, which was exactly the same as the Bose HU for '99. It should say 1M31 or 1M32 somewhere on the unit (upper right IIRC), that's what I had.

The Pioneer I selected is not significantly better, it's the most reasonably priced replacement I could find. It does have a couple of issues: when it's on, the antenna is up, no matter if I'm listening to CD's, the Empeg, or the Radio; and the headlight switch appears not to be working. The latter issue seems like it could be repaired witht the proper wiring, I just haven't gotten around to it.

>>I see. The P-BUS connector let him connect the RCA cables off of the Empeg harness? And the other end of the P-BUS plugged into the Pioneer HU, right? <<

Yup, that's the way it was done.

If this helps, I'm thinking about just moving the Pioneer to my OTM then putting the Empeg with a AM/FM tuner I have for it into the Miata. I'd loose CD functionality, but then that only matters between the store and my ripping PC. Heck, if I could find a simple handheld radio that received AM/FM/CB/FRM that I could attach to the AUX on the Empeg I'd be set! I'd whip out the handheld whenever I needed it (~1 / month) and be happy with the Empeg in between.