Here's an easy-squeezy no soldering power cable to go from
a 9.6V Race Car battery to a Hosa box.
All Parts from Radio Shack
Part 23-445 - 9.6V Battery Pack and RC Car Connector Repair Kit $2.99
(has two of the RC connectors with crimp on thingies)
you might want to throw some tape on after crimping, but
these ended up pretty secure...
Part 273-1743 - Replacement Adaptaplug Socket $2.99
(to crimp n the end of the RC connectors, above)
Part 273-1706 - Adaptaplug C $4.99
(this is the one I chose, fits nicely. bagtagsell says Adaptaplug B works as well)
crimp, connect and yer ready to go....
I'm sure this can be done cheaper or easier, but this worked for me.