Hi Per-Tore,
I believe that Elecraft uses CAT commands to turn the AF level up and down. This would keep the remote
and local K3's in sync. Your idea is not bad, so maybe you can try it out to see if the k3/0's AF amplifier
can make the output loud enough. It can't hurt to try, but I don't think it will be loud enough to use.
Of course, this sort of discussion should be on the Elecraft reflector if you need more details.
73,
Mitch DJ0QN / K7DX