Some years back, when hooking up an external speaker (Alpha Delta VRC)
to my Drake SW8, I had to use a special adapter because the Drake's
audio output "floats" with regard to ground.

I've never really used external speakers with any other radios other
than my SW8 and tabletop units. Recently, however, I had thought to
use an external speaker with some portable units: Sony SW77 & 2010,
and Eton E1. I'm guessing that I don't need to worry about "floating
output" with regard to these units, but I'd like to confirm about this
before hooking 'em up to an outboard speaker. Can anyone here confirm?

Secondly, with regard to the Drake SW8, I've used the aforementioned
adapter which allows this receiver to be used with an outboard speaker.
The adapter is a 1/4'' male to female mini plug with a small wire that
connects to the receiver's chassis. Up to now, I've only used this
adapter when running the SW8 off of AC. I would ask anyone who might
know, is use of such an adapter equally adequate for protecting the SW8
from adverse affects when hooking the receiver up to an external
speaker when the receiver is being run off of batteries?

Thanks for any help provided,

Junius