I, and I'm sure quite a few others, would have recommended a simple
transistor stage as a solution except for your request in the original
posting about not wanting to suffer too much power loss. If your only
concern is the amount of audio power you get out, and you're not
concerned with overall power consumption, then an active stage is
certainly an alternative. The type of circuit you choose would depend on
how much efficiency you need and how much audio output power you
require. An emitter follower is the simplest but least efficient; a
comlementary-symmetry stage would be more efficient but more complex.

Roy Lewallen, W7EL

Paul Burridge wrote:

Thanks, Roy. Looks like there's rather more to it than I imagined. :-(
I wonder if Reg has written a program to design impedance
transformers? :-)
I woke up this morning, having given it due thought overnight and
thought I'd got it cracked. But that was until you said the primary
inductive load Z should be many times the design load Z. Oh well,
back to the drawing board, I guess. Looks like it's gonna take a lot
more wire and a lot more turns than I'd thought. OTOH, I could just
stick an emitter follower stage on the end of the amp chain and have
done with it. :-/