An update - I have discovered (discovered? yeah, go figure) that the Honda antenna connector does NOT plug in "all the way" to the antenna amplifier adapter.

And so ... now I'm wondering could THIS be the reason I'm not getting the best reception?

What's unclear at this point is whether it isn't plugged in all the way because the Honda plug's tip is too long or because the adapter that it plugs into is too narrow inside, causing the tip not to make contact (or does it not matter - I'd think it does in that case).

Hmm. Why would Honda (or this adapter mfgr.) make non-standard plugs/receptacles? Question-beggers-R-us.